Hiking Mount Diablo 8 Popular Hikes 10 Short Walks 10 Moderate Hikes 10 Demanding Hikes Archived Hike Articles Biking Horseback Riding Points of Interest Activities at Mount Diablo State Park Mount Diablo has many great activities. Here you will find information about fun activities you can do while visiting Mount Diablo. More More More Hiking Mount Diablo One of the pleasures of living near Mount Diablo is the variety of hiking and walking opportunities that it offers. You can drive to the summit and spend an easy 20 minutes walking along the Fire Interpretive Trail or you can hike a round-trip from Mitchell Canyon in Clayton to the top and back again -- about an eight-hour, 3400 ft elevation gain (and drop) strenuous work-out. Biking Mount Diablo Mount Diablo State Park is an excellent place to mountain bike. This guide is designed to help off-road cyclists enjoy the park safely without damaging its sensitive environments. Mountain bicyclists share the backcountry with hikers and horseback riders. It's important to be considerate of other recreational users. Horseback Riding Mount Diablo Most state park trails are equipped with unlocked gates allowing access across fence lines. Ask rangers for current information. Points of Interest in Mount Diablo Most first-time visitors to Mount Diablo head straight to the summit to enjoy the famous view. Summer days are sometimes hazy, and the best viewing is often on the day after a winter storm.

Coyote and Quail Focus on Coyote and California Quail Mt. Diablo's Other Inhabitants! by Keith Patterson Reprinted from the Mount Diablo Review , Fall 2000 The Coyote (Canis latrans ), a member of the dog family, is native to California. It closely resembles a small German shepherd dog with the exception of the longer snout and bushy, black-tipped tail. The coyote’s high-pitched, yodel-like yapping can frequently be heard at night. Coyotes are extremely adaptable and can survive on whatever food is available. They hunt rabbits, mice, birds and other small animals as well as young deer and sheep. They will also feed from the carcasses of dead animals and will accept handouts from people in the form of table scraps, pet food and garbage. Coyotes are found throughout California, from deserts and mountain habitats to urban areas. They have certainly become much more common on and around Mount Diablo in recent years. Problems occur when people begin feeding coyotes, either deliberately or inadvertently. Coyotes will quickly lose their natural fear of people and become bold, even aggressive. Pets are sometimes injured or killed by coyotes. Coyotes on Mount Diablo tend to live alone or in breeding pairs. Alone, in pairs or in packs, coyotes maintain territories by marking with urine. They also use calls to defend territories. Several solitary males may gather to court a female at the start of the mating season, but the female forms a relationship with only one of them. The mating season extends from January to March so that the pups are born in spring when the food is abundant. The pups are born blind in a natal den. After about 14 days their eyes open and they emerge from the den a few days later. The pups suckle for five to seven weeks; at three weeks they start with semi-solid food regurgitated by both parents. At the end of the summer they can care for themselves and may leave or stay with their parents, depending on food availability and habitat conditions. If you happen upon coyotes on the mountain steer clear of them as much as possible and vacate the area as soon as possible. If they approach you, and only if, make loud noises and wave your arms to scare them away. The coyote is one of the fastest mammals in North America, reaching speeds of up to 38.4 mph. Coyotes can breed with wolves and domestic dogs. A dog-coyote mix is called a ‘coydog’. Many Native American tribes consider the coyote a maker of fateful decisions with the power to transform beings and objects. The California Quail (Callipepla californicus ) was selected by the State Legislature in 1931 as the official state bird of California. Sometimes called valley quail, this gallinaceous (chicken-like) bird is widely distributed over approximately 70% of the state where suitable habitat remains. It is one of the most popular upland game species enjoyed by sportsmen (although not on Mt Diablo) and birdwatchers alike. The quail prefers nesting in woodland-brush areas interspersed with grasslands. When not nesting or brooding young, California quail roost in tall bushes and trees at night. In late summer, fall and winter family groups may join together, forming coveys of 50 to 100 birds or more. In early spring the coveys break up into pairs and look for suitable nesting sites. The species is monogamous; the male takes only one mate during the season. He is a very attentive mate, for he will assist in the incubation of eggs and in the care of young. He is also an alert sentinel warning his mate and young when danger approaches. The nest is usually constructed on the ground in a shallow depression lined with grass, and is under some protective cover such as a bush, log or weeds. The average clutch size is 10 to 15 creamy eggs that are lightly spotted with golden brown although there has been a tendency towards lower clutch sizes in this area in recent years. The incubation period is 21 to 22 days. The young are ready to leave the nest shortly after drying off. The diet of California quail consists mainly of seeds during the dryer seasons and greens in the winter and spring. The chick’s diet is composed of insects, greens and seeds until they are several weeks old, at which time their diet becomes similar to that of the adults. The California quail is very vocal. When birds are busy feeding, a number of different calls may be heard at close range. A scolding call is often given as birds scurry from danger. The year-round assembly call is most commonly heard and is a loud, clear "cuc-ca-coo". It has been interpreted as "chi-ca-go", "come-right-home", "get-right-up" and many other expressions. During the breeding season from April to July, the male, perched on a post, repeats at intervals a single resonant note. The large flocks post sentinels to danger. Photo credits - Michael Evan Sewell (Coyote) and Dave Furseth (Quail) Some of the information for both these descriptive pieces was taken from California Department of Fish and Game literature Back

Guide to Mount Diablo Geology Part I: The Rocks of Mount Diablo - Their Type and History Rising 3,849 feet, Mount Diablo forms a prominent feature in the East Bay landscape. Our understanding of the geological history of the rocks and structure of Mount Diablo has undergone major changes during the past 30 years, and even now geologists are still trying to unravel the complicated history of the mountain. This complex history is not unique to the mountain, but to our region as a whole, since Mount Diablo has been caught up in the processes that have shaped the Coast Ranges for millions of years. Perhaps the most salient fact is that, although the rocks of which it is composed are very old, Mount Diablo only began rising recently in geological terms. The rocks are old, but the mountain itself is young. Wind Cave | Roi Peers To better understand the complex geology of Mount Diablo, it is useful to divide the mountain’s rocks into three main groups. Each group has a different history and is characterized by different types of rocks. Group 1: Mount Diablo Ophiolite (Jurassic ) Group 2: Franciscan Complex (Jurassic and Cretaceous ) Group 3: Great Valley Group (Jurassic and Cretaceous ) and Younger Sedimentary rocks (Cenozoic ) Plate tectonics played a major part in the formation of the Mesozoic rocks of Mount Diablo. We now recognize at least 11 separate major plates of oceanic crust and rigid upper mantle rocks around the globe. These plates “float” on a layer of semi-molten rock, all moving against and jostling each other, creating new land forms in the process. Continents ride atop these ocean plates, being rafted along as the plates move. New oceanic crust is being continually created by the eruption of submarine volcanic material forming along ocean-spreading ridges such as the Mid-Atlantic Ridge. To compensate for the newly created oceanic crust, older existing oceanic crust is driven beneath the continental crust at subduction zones, and recycled into the earth. Highly sheared serpentine | Roi Peers Group 1 - Mount Diablo Ophiolite (Jurassic-Cretaceous ) It is generally believed that near the close of the Jurassic a subduction zone developed along what is presently represented by the modern California coast. The oceanic crust caught between this subduction zone and an earlier shoreline in the ancient Sierra foothills was preserved as the Coast Range Ophiolite and later partially exposed. Ophiolites are thought to form at oceanic spreading centers in the middle of the oceans, associated with oceanic island chains (arcs), or in narrow oceans such as the Gulf of California. Ophiolites generally form a uniform vertical rock sequence consisting, from bottom to top, of ultramafic peridotite from the top of the mantle, mafic intrusive gabbros and/or diabase that formed one or more miles below the sea floor, and mafic extrusive rocks, often in the form of pillow lava extruded beneath water. The rocks of this old ocean crust on Mount Diablo have been named the Mount Diablo Ophiolite and is considered a fragment of the Coast Range Ophiolite. The Mount Diablo Ophiolite underlies the mountain north of a line drawn from Long Ridge through Murchio Gap, encompassing the Zion Peak rock quarry, Mitchell Rock, and Eagle Peak. Radiometric and fossil-age determinations date the ophiolite as having been formed approximately 165 million years ago during the Mid-Jurassic. Franciscan graywacke sandstone | Roi Peers Mount Diablo Ophiolite Basalt: The basalt, which makes up the upper part of the Mount Diablo Ophiolite, is mostly interbedded pillow basalt lava flows. As the lava erupts under water, the outer surface of the flow “freezes” in contact with the water. More lava breaks through and again the outer surface “freezes.” This process leads to the accumulation of “pillow” structures and the resultant rock is referred to as pillow basalt or pillow lava. The basalt has a microscopic crystalline texture with a black to greenish-brown color, weathering to a yellowish-brown to dark reddish-brown soil. Well-developed pillows can be seen on Mitchell Rock. Mount Diablo Diabase: The pillow lavas are fed by a series of vertical fissures, or dikes, that allow the molten rock from below to reach the surface. The molten material in the dikes solidifies into a rock called diabase, which has the same chemical composition as basalt, but with a coarser texture. Diabase is exposed in quarries at Mt. Zion and on Eagle Peak. Mount Diablo Serpentinite: Serpentinite is a rock frequently found in association with an ophiolite. Serpentinite is derived from the basal portion of the original ocean crust and uppermost part of the mantle, but has been metamorphosed by hydration from ocean water circulating through fractures in the ocean crust. Serpentinite forms by addition of water to minerals in peridotite, changing them from olivine and/or pyroxene to the serpentine minerals antigorite, chrysotile and lizardite. Serpentinite, incidentally, is California’s state rock. On Mount Diablo, serpentinite occurs in several localities. The largest is the prominent east-west band that runs through Murchio Gap extending west along Long Ridge, separating the ophiolite on the north from the Franciscan rocks exposed in the central core of the mountain to the south. This band is characterized by a noticeable change in vegetation due to the high magnesium content of the serpentinite. Exposures of the serpentinite are typically pale green to greenish-gray, locally black, weathering to grayish-orange. In addition to the highly sheared serpentinite, ultramafic rocks of harzburgite (a variety of peridotite) and pyroxenite are present in this band as well, but are less sheared than the serpentinite. The body of pyroxenite exposed along the Burma Road Trail on Long Ridge is coarsely crystalline, sparkling in the sunlight as you walk along the trail. Exposed blocks of massive harzburgite on the westerly end of Long Ridge frequently contain veins of fibrous chrysotile. There are several pods of silica carbonate rock (altered serpentinite) found in association with the mercury mines on the northeast flank of the mountain and other scattered locations along the serpentinite band. Franciscan beds of folded red chert | Roi Peers Group 2 - Franciscan Complex (Mesozoic ) The central Mount Diablo summit area and North Peak is underlain by an assemblage of Mesozoic rocks that have been a puzzle to California geologists for years. Our relatively new understanding of plate tectonics and subduction has finally provided an important clue to unraveling this mystery. This diverse complex of rock types is common up and down the coastal ranges of California and has been given the name Franciscan Complex. The processes of subduction can account for the mixing of such a wide variety of rock materials. The Franciscan Complex records over 140 million years of uninterrupted east-dipping subduction, during which the Franciscan formed as an accretionary complex. As the oceanic plate subducted beneath the continent, part of the upper section of the ocean crust (pillow basalt) and the material riding on the plate (chert, graywacke, shale, small islands, and sea mounts) were scraped off the upper part of the subducting plate, mixed together, partially subducted and accreted on and under the continental crust. Mount Diablo and North Peak are composed of faulted blocks of resistant basalt and chert with some graywacke and minor shale, and are expressed topographically as rugged and jagged rock masses. Wrapping around the two peaks in a rough “figure 8” shape are the more gentle treeless slopes of “mélange.” Such a diverse mixture of rocks, is called a "mélange" by geologists from the French for "mixture". The Franciscan mélange is essentially a chaotic mixture of an intensely sheared sandstone and shale “paste” in which are embedded blocks of basalt, chert, and graywacke along with rare exotic rocks. It is often difficult to distinguish between the mélange topography and local landslides. Franciscan rock accretion ceased with the ending of subduction in our area. Franciscan-like rocks are currently forming north of Cape Mendocino offshore or beneath the continent where the oceanic Juan de Fuca plate is still subducting beneath North America. Recent studies using modern dating techniques and temperature history studies suggest that the Franciscan Complex appears to have undergone metamorphism around 108 million years ago at a depth of approximately 12 miles. As a result, the Franciscan rocks are frequently referred to as metabasalt or metagraywacke reflecting a history of metamorphism by heat and pressure deep underground. Franciscan basalt: The blocks of basalt exposed in the Franciscan on Mount Diablo are altered oceanic pillow basalt. On the surface the rock weathers to a dark yellowish-brown to dark reddish-brown while fresh exposures are grayish-green to light olive drab. It is locally called “greenstone.” The green color comes mostly from chlorite, a green alteration mineral. The basalt blocks in the Franciscan are believed to be fragments scraped off of the upper part of subducting basaltic oceanic crust. Franciscan chert: The chert bodies in the Franciscan form prominent dark red exposures and talus slopes. Made up of silica, they are resistant to erosion and form such features as Devil’s Pulpit and Turtle Rock. Typically red in color (green and white less common), the chert layers are typically interbedded with reddish-colored shale. These banded rocks are often referred to as “ribbon chert.” The red color is derived from iron oxides. The chert in the Franciscan was formed far out at sea. Silica skeletons of minute ocean animals called radiolaria settled to the ocean floor forming a silica ooze that ultimately solidified into chert. The chert continued to slowly accumulate on top of the ocean floor as the ocean crust drifted away from the spreading center on its long journey toward subduction. The Franciscan chert ranges in age from 190 myo (million years old) to 90 myo, representing 100 million years of accumulation. Franciscan cherts are formed from the tiny (0.5 to 1.5 mm) silica shells of radiolaria. Many of these radiolaria are tropical species indicating that the sediments were deposited near the equator and were later transported northeastward by plate movements. Franciscan graywacke: Graywacke is less common on Mount Diablo than the greenstone and chert. It is typically fine-to medium-grained and massive (no stratification or bedding visible). It breaks along distinct joint planes, which helps distinguish it in outcrop from the more “shatter fracturing” of the greenstone. The graywacke consists mainly of angular quartz, plagioclase feldspar, chert fragments, and dark volcanic rock fragments. Calcite and quartz occur commonly in the criss-crossed white veins. The graywacke is younger in age than the greenstone (basalt) or chert, ranging from 90 to 108 million years in age. These rocks are thought to have formed in a subduction trench environment off the coast of North America (some researchers suggest Mexico, subsequently moving north). Franciscan shale: Approximately 10% of the Franciscan on Mount Diablo is made up of shale, most of which has been altered to argillite as a result of the earlier period of metamorphism. Most of this clay-sized material was probably deposited in less turbulent current conditions in association with the graywacke deposition. Franciscan exotic rocks: The most common so-called exotic rock present on Mount Diablo is a glaucophane schist, or “blueschist,” named for the noticeable blue color of the glaucophane. Blue schist is largely altered basalt and reflects a history of hi-pressure/low-temperature metamorphism, a condition found in subduction environments and rarely any other place. On the Summit Road as you drive toward the summit, just past the Rocky Point Picnic area, you will notice a dark blue-black boulder of blueschist about five feet across protruding from the bank on the left side of the road. Group 3 - Great Valley (Jurassic - Cretaceous ) and Younger Sedimentary Rocks (Cenozoic ) The name Great Valley Group refers to the thick sedimentary rocks of Upper Jurassic through Cretaceous age that were deposited between the ancestral Sierra Nevada to the east and the subduction zone to the west on top of the ophiolite basement that underlies California’s central valley. The Great Valley sequence is composed mostly of deepwater marine shale, sandstone and some conglomerates accumulating to a thickness of 60,000 feet near the western margin of the present day Great Valley, and then, in our area, thinning toward Mt. Diablo. The Upper Jurassic Knoxville Formation is 140 million years old and are the oldest beds of Great Valley in this area. Great Valley deposits on-lap the Mount Diablo area and thinner deposits intermittently covered it during this time. The general interpretation of these rocks is that they were deposited in the submerged central valley as intermittent underwater "turbidity currents" and the deposits are called turbidites. To summarize the Cenozoic in this area, it is perhaps easiest to think of the central valley of California as a low elongate basin, flooded intermittently by an encroaching shallow sea, and slowly being filled by sedimentary material eroded from the surrounding exposed land masses, primarily the “Sierra.” During the latter part of the Tertiary, newly formed highlands to the south (Diablo Range) and in the area of the present day San Francisco Bay also acted as source areas. The Mount Diablo area seemed to represent a persistent “high,” underwater, but less deep than surrounding areas and periodically exposed to erosion. Many of the formations seem to shoal out on the flanks of this area and when submerged, the strata thin over this “high.” The area, however, was not a “mountain” as we see it today, but rather a land of low relief intermittently submerged well into the Pliocene. Paleocene Rocks (55.5 - 65 million years ago) There are few Paleocene deposits present in our area indicating that the region was probably above sea-level and undergoing erosion following the close of the Cretaceous. The only nearby rocks of this age are restricted to the north side of the mountain outside of the park. Eocene Rocks (33.7 - 55.5 million years ago) During the Eocene , the climate warmed, resulting in heavy “ancestral Sierra” weathering that yielded large quantities of sands that washed into and across the Central Valley providing material to the Eocene deposits of Mount Diablo. A shallow marine basin, a sandy shoreline, a swampy backwater area—all existed in this area at different times or at the same time in different places. On the north side of the mountain, the Eocene is present in the Black Diamond Mines Regional Park. These strata contain coal beds and glass sands and have been described as a near-shore lagoonal swamp or tidal flat estuarine environment. On Mount Diablo, Eocene deposits form the ridges of tan-colored sandy rock formations that wrap around the south and west side of the mountain. These sedimentary rocks have been given the name Domengine Formation and are well exposed at Castle Rock, Rock City, Knobcone Point, and Cave Point. These sands on the south side of the mountain are characteristic of deep offshore slope deposits. They represent deep erosion of the ancestral Sierra highland spreading over the Mount Diablo area as the ocean deepened westward. Some Domengine beds represent shallower near-shore deposits that contain beds rich in Turritella fossils (marine snails). These massive sandstone beds weather easily forming features such as caves and open tunnels. Rock City, easily accessible on the South Gate Road, is a good place to view these unusual features. Turritella Fossils | Mike Woodring These massive sandstone that form the Wind Cave beds weather easily forming features such as wind caves and open tunnels. Unusual "cannonball concretions" can also be found in these sandstone beds. Rock City is a good place to view these unusual features easily accessible on South Gate Road. Oligocene Rocks (23.8 - 33.7 million years ago) The only Oligocene rocks in the area is the Kirker Tuff on the north side of the mountain outside the park boundary. Wind Caves | Roi Peers Miocene Rocks (23.7 - 5.3 million years ago) On the south and west sides of the mountain, the depositional contact between the Eoceneand the Miocene rocks can be recognized by the abrupt change from clean, thick-bedded, light tan sandstone in the Domengine formation (Eocene) to poorly sorted, dark gray, pebbly sandstone of the marine Miocene rocks. There is a large gap in the geologic time record between these rock units, representing erosion or non-deposition. The interval of missing time and rock equivalents includes the upper Eocene, the entire Oligocene and the lower (or earliest) Miocene. During middle Miocene time, the general drainage was directed from the east into an open ocean to the west, a pattern similar to the deposition of the earlier Eocene. By about 10 mya (million years ago), subduction had ended in central California and there was a major change in the pattern of deposition. A highland developed to the west and the Diablo Range south of Livermore began to rise. The Mount Diablo area began to accumulate marine and later non-marine deposits from these sources. Now steeply tilted upward from an original horizontal orientation, the vertical beds form the prominent “hogbacks” on Fossil Ridge and Blackhawk Ridge. Building material quarried from Fossil Ridge was used to construct the summit museum building, and numerous clam and oyster shells can be seen in the exterior walls of that building. These fossiliferous beds are called the Briones Formation. Following Briones deposition, the direction of sediment transport shifted again, bringing sands derived from the east, rich in volcanic material washed from the Sierra highlands. These volcanic sands have been named the Neroly formation. They form the grass-covered rounded hills immediately south of the underlying ridge-forming Briones strata on the south, and can be found on the west and north sides of the mountain as well. Andesitic Neroly sandstone alters easily, and in most places the sand grains are coated with a thin layer of bluish clay that is clearly exposed in an often visited site in Shell Ridge Open Space in Walnut Creek. Beds rich in fossil marine shells are well exposed at this site and also in Sycamore Canyon on the southern flank of Mt. Diablo. Around nine million years ago, during the late Miocene, the sea again receded from the Mount Diablo area, marking a permanent change from marine deposition to non-marine stream and lake deposition. One of the nine million-year-old stream deposits on the south side of the mountain has captured and preserved an abundant and diverse collection of animal fossils. The Blackhawk Ranch Quarry has yielded numerous vertebrate fossils of horses, rhinos, camels, and smaller animals. A large mastodon skull, a Gomphotherium , has been removed from this site. All give evidence that late Miocene mammals abounded in the newly created forests and flood plains stretching away to low hills to the west and south. There are several volcanic tuff deposits in the late Miocene and Pliocene derived from the volcanic fields of Sonoma County. There was still no Mount Diablo at the time. Plio-Pleistocene to recent rocks (5.3 million years ago to present) Non-marine deposits continued to collect in the area during Pliocene time (5.3-1.8). It was during Plio-Pleistocene time, by 4 mya and continuing to the present, that Mount Diablo was formed as a topographic feature. From that time on, Mount Diablo has been feeding erosion materials into surrounding valleys. Pliocene sources were predominantly from Great Valley rocks. Pleistocene sources were predominantly from Franciscan, indicating unroofing and erosion of deeper terranes. The 4.83 million-year-old Lawlor Tuff is a widespread marker bed around the mountain. The fact that it was laid down on a relatively flat landscape and is now steeply folded indicates that Mt. Diablo must have begun its growth after the tuff was deposited. Part II: Forming the Foundation - Mount Diablo's Tectonic History Although Mount Diablo is old in terms of its rock history, it is very young as a topographic feature. The rising of Mount Diablo to its present height is the result of a complex interplay of tectonic forces. The Franciscan Complex presumably underlies all of Contra Costa County. It was emplaced below the Coast Range Ophiolite by accretionary faulting during Cretaceous time, so the contact between the Franciscan and Coast Range Ophiolite (locally called the Mount Diablo Ophiolite) as well as the overlying Great Valley Sequence is everywhere a fault plane. This fault is known as the Coast Range fault. Recent field studies suggest that following the emplacement of the Franciscan Complex at depth in this area, the rocks underwent a period of metamorphism. This appears to have occurred at depths of approximately 12 miles. During late Cretaceous through early Eocene time, the overlying cover rocks were significantly thinned by extensional faulting along the Coast Range Fault plane and ductile thinning in the serpentinite component of the ophiolite. As a result of this slow structural thinning of the overburden, the Franciscan rocks of the future mountain rose vertically to a depth of around two miles. There appears to be no evidence that these rocks were above sea level during this period. The final two miles of uplift and exhumation of the Franciscan Rocks occurred during Pliocene to present time. It was during this last phase that the Franciscan rocks, and overlying Great Valley strata, were folded by compressional forces associated with what is believed to be a blind thrust fault beneath the mountain. These geological processes have created a complex uplifted compressional asymmetric fold that has been moving southwest on the blind thrust. The recognition of the possible existence of a blind thrust fault under Mount Diablo has resulted in the issuance of an advisory by the USGS in September, 1999, predicting a four-percent probability of a 6.7 or larger earthquake occurring on the blind thrust fault underlying the mountain. Geologists believe the mountain is still rising at about 2 millimeters per year. Extensive erosion has exposed the Franciscan in the center of the fold to produce the majestic Mount Diablo we see today. Part III: Mount Diablo Mining History - Boom to bust The most important minerals and rocks that have been mined or excavated on and around Mount Diablo include mercury, diabase, graywacke, white sands, coal, blue schists, travertine, copper, and farther north and east, gas and oil. Mercury Mercury has been mined on the northeast flank of Mount Diablo off and on since its discovery in 1863. Prior to that, Indians used the colored mineral for ceremonial purposes. The mercury (also referred to as quicksilver) occurs in the form of cinnabar (red mercury sulfide) and metacinnabar (a black mercury sulfide). The host rock for ore is silica-carbonate rock, itself formed from the hydrothermal alteration of serpentine, lying in the boundary fault zone that separates Franciscan from Great Valley rocks. The silica-carbonate rock is made up of varying quantities of silica (chalcedony and opal) together with magnesian carbonates and stained rusty red by alteration of iron sulfide minerals. The rock is commonly spongy in appearance. Topographically, silica-carbonate rock forms resistant outcrops. It is believed that the mercury minerals were deposited from hydrothermal solutions which formed mostly in fractures in the silica-carbonate rock. Ryne Mine produced most of the cinnabar while metacinnabar was produced at the Mount Diablo Mine. A man named Welch discovered cinnabar at what is known as the Ryne Mine in 1863. It operated for about 10 years before becoming uneconomic. In 1933 it was discovered that black metacinnabar in the area known as the Mount Diablo Mine also contained mercury and was more abundant than cinnabar. The demand for mercury during the second world war resulted in an expansion of operation that was to continue until 1958 when mining operations again ceased. It is estimated that about $1,500,000 worth of mercury was extracted from the mines. Unfortunately a continuing legacy of the mining is the acid mine water emptying into and contaminating Marsh Creek. Building Stones and Rip-rap The diabase quarries on the northside of the mountain (Zion Peak) are currently being excavated for crushed rock and rip rap material. There were several excavations in graywacke on the northside of the mountain for the same purposes, but they are now abandoned. Blue schist from the Franciscan rocks on Mount Diablo yielded good dimension stone and was popular for building construction due to its color. Copper and Precious Metals About 40,000 pounds of copper was produced from the mines in the diabase in the 1860's, but there is no activity now. Minor amounts of gold and silver associated with the copper were also produced. It was rumored that the best area to discover gold or silver was in the Back Canyon area (unfortunately inside the park boundary). Travertine Travertine, a finely crystalline massive calcium carbonate deposit frequently associated with hot springs, was quarried along the northside of Mount Diablo (Lime Ridge) for many years by the Cowell Cement Company. Coal and White Sand North of Mount Diablo and outside the park in the Black Diamond Mines area, lignite coal beds in the Domengine Formation were the largest known and most extensively mined Coal deposits in California. From the 1860's to the beginning of this century, the Mount Diablo coal field supplied coal to the rapidly expanding urban and industrial centers of the San Francisco Bay area. Finally closed as newer and cheaper energy sources were discovered, during its lifetime the mines produced approximately 4,000,000 tons of coal valued between $15 and $20 million. At the base of the Domengine Formation exposed in the Black Diamond Mines Regional Park, there is a thin section of white sands called the "Ione" sands, a description carried across the Central Valley from major white sand deposits in the Ione Formation on the east side of the Valley. The sands appear to be continuous across the valley subsurface and of equivalent age. The white sands, that were used for making glass, were mined from two deposits in the area from 1920 until 1949 when they ceased operation. The caverns are a fascinating place to visit on guided tours. Gas and Oil The Domengine Formation also acts as a reservoir for natural gas and the Martinez Formation produces oil in the subsurface northeast of Mount Diablo.

Contact Us Success! Message received. Send 925-927-7222 Mount Diablo Interpretive Association P.O. Box 346 Walnut Creek, CA 94597-0346 Sign Up For Mailing List

Mount Diablo State Park offers an extensive network of trails and fire roads--some are ideal for easy, scenic rides, while others are more challenging, testing both the horse and the rider for endurance and ability to navigate rough terrain. The Mount Diablo Guide , 3rd Edition 3 cups Blueberries 3 cups Flour 1½ cups Butter Mount Diablo State Park offers an extensive network of trails and fire roads--some are ideal for easy, scenic rides, while others are more challenging, testing both the horse and the rider for endurance and ability to navigate rough terrain. The Mount Diablo Guide , 3rd Edition Horseback Riding on Mount Diablo Most state park trails are equipped with unlocked gates allowing access across fence lines. Ask rangers for current information. Note to Equestrians The Mary Bowerman Trail and the Summit Trail above lower summit parking lot. The following trails are closed to horses: Two large staging areas for equestrian use: Mitchell Canyon staging area is located on the north side of the mountain near Clayton, and the Macedo Ranch area is located on the west side of the park in Alamo. Most other trailheads are suitable for unloading horses with the exception of those trailheads with only limited parking along road shoulders. Water Troughs Water troughs can be found throughout the park. However, these are not maintained and may be empty. Be prepared and carry water for you and your animal. Horses have the right-of-way on trails Hikers are expected to step to the side of the trail and avoid sudden movement that might frighten the animals. Horse Camping The park has one approved horse camp, BBQ Terrace. It will hold up to 50 horses and 50 people. Reservations can be made through the regular camping reservation system: ReserveCalifornia Equestrian Links California State Horsemen's Association, region 5

MDIA Annual Report The Annual Report provides a yearly summary including Board and Committee reports, financial reports, and a summary of accomplishments and active projects. The Report is distributed to MDIA Members in the first quarter of each year. Reports are also available for online viewing/download. 2025 Annual Report 2024 Annual Report 2023 Annual Report 2022 Annual Report 2021 Annual Report 2020 Annual Report 2019 Annual Report

Board of Directors President Steve Smith Steve grew up in Danville and has been an avid hiker and outdoor enthusiast his whole life. He is a docent, hike leader, back-country rover, leader of the Maintenance Volunteer Group, and member of the Trash Removal Project. He began volunteering on the mountain after completing a quest to hike all 162 miles of trails within the park. Vice President Mike Brandy Mike is always drawn to the outdoors for inspiration and renewal. As a Mount Diablo State Park volunteer for the last four years, he is currently engaged in co-managing the Mitchell Canyon Visitor Center, always trying to enhance the docent training and the visitor experience to the park. He also volunteers on the Trash Removal Project (TRP) team. He usually cycles or hikes every week on the mountain. Treasurer Dan Fitzgerald Dan grew up in Concord with a view of the mountain and spent some time exploring it with Michael Marchiano. When he retired, Dan completed the State Parks volunteer training and became an active member of the Trash Removal Project and a visitor center and roving docent. Dan also enjoys nature photography. Secretary Dan Sandri Dan has lived in the East Bay for nearly all of his life, and Mt. Diablo has always been his favorite hiking place. Dan has a B. S. degree in Entomology and enjoys observing and photographing insects, birds, reptiles, as well as other plant and animal life. Upon retirement, Dan became a volunteer at Mitchell Canyon Visitor Center, and a back-country rover. Dan enjoys interacting with visitors, learning and writing. Board Member Mark Brauer Mark has lived in the East Bay for the last 35 years and has enjoyed hiking at Mount Diablo since he moved here. For the past six years he has volunteered his time as a docent and as a rover at Mount Diablo. He particularly enjoys interacting with the park's visitors and helping them discover the best places to visit in the park. Mark set himself the goal in 2013 to hike every trail in Alameda and Contra Costa counties and after 8 years completed that task. Of all the parks and open spaces in the East Bay he finds the most enjoyment from visiting Mount Diablo. Board Member Julie Braun Martin Julie, an educator for many years with a passion for conservation and serving youth, enjoys walking on the mountain and serving at Mitchell Canyon and assisting with publications. Board Member Leslie Contreras Living in the shadow of Mount Diablo all her life, Leslie has always had a passion for the mountain. She contributes to MDIA as the event coordinator for the hiking program and as co-manager of the Mitchell Canyon Visitor Center. Board Member Linda Kwong Linda has lived in Alamo since 1997. Her connection to the mountain started after a neighbor took her on a bike ride to the Summit over 7 years ago. Now she is a regular visitor on the mountain, often riding 3-4 days per week. Photographing all four seasons and engaging with both the park visitors and staff are her favorite activities. Her goal is for all park visitors to have a safe, memorable and fun experience during their visit on Mount Diablo. Board Member Dick Nicoll A long time local resident, Dick loves everything outdoors. He coordinates publications, serves at Mitchell Canyon, works on the Trash Removal Project, and organizes road repairs. He has completed the California Naturalist Program. Board Member Michele Stanton Lambert Michele Stanton Lambert was raised in the Bay Area, left after high school, and happily returned in retirement. She is a docent for the Mitchell Canyon Visitor’s Center, a frequent hiker on the mountain, and co-manager of the Mitchell Canyon Visitor’s Center. She has loved Mt. Diablo since childhood, loves sharing the mountain with visitors, and is passionate about its native plants. Board Member Steve Viarengo Steve has been a Danville resident since 1997. In that time he has spent many hours hiking and biking on Mount Diablo and enjoying time with his family exploring Rock City. He began volunteering in 2022 and found that the volunteer activities he enjoyed the most involved being with visitors out in the park. In addition to time on the trails he enjoys kayaking on Lake Tahoe and traveling with his wife. Committee Members & Lead Archives Maintains print archives Lead(s): Dan Sandri Other Members: Steve Smith Audible Mount Diablo Coordinates development of Audible Mount Diablo/Mount Diablo "Shorts" Lead(s): Steve Smith Other Members: Wally De Young; Kendall Oei; Joan Hamilton Contracts Develops and reviews MDIA contracts Lead(s): Dick Nicoll Other Members: Steve Smith Corporate Governance Updates and maintains the documents contained within the MDIA Board of Directors Handbook Lead(s): Vacant Other Members: Dan Sandri Education Encourage school field trips by adding content to MDIA website that would assist teachers in planning trips to MDSP. Lead(s): Julie Braun Martin, Dick Nicoll Other Members: Finance Review financial records and bank statements Lead(s): Dan Fitzgerald Other Members: MDIA Executive Committee Fundraising Develops fundraising strategy to support new MCVC Lead(s): Mike Brandy, Dick Nicoll, Julie Braun Martin Other Members: Judith Parker, Gary Parkhurst, Dan Sandri, Steve Smith, Steve Viarengo, Tere Dixon Hikes Recruits hike leaders; advertises and leads hikes in the park Lead(s): Leslie Contreras Other Members: Ken Lavin Insurance Negotiates appropriate insurance coverage and manages insurance-related matters Lead(s): Linda Kwong Other Members: Interpretive Displays Designs and fabricates interpretive panels and visitor center displays in conjunction with MDSP Lead(s): Steve Smith Other Members: Mike Brandy, Dick Nicoll, Mark Brauer, Julie Martin MCEC Capital Committee Recommend architects to prepare conceptual drawings for new MCVC; apply for grants for MCVC Lead(s): Mike Brandy, Dick Nicoll Other Members: Julie Braun Martin, Steve Smith Marketing, Advertising and Publications Publishes Mount Diablo Review, MDIA annual report, and other MDIA publications Lead(s): Dick Nicoll Other Members: Steve Smith Membership Maintains membership list; prepares membership packets and acknowledgements. Lead(s): Julie Braun Martin Other Members: Steve Smith, Dan Fitzgerald, Dick Nicoll Merchandising Orders and maintains merchandise to sell at SVC, MCVC and online; maintains inventory; fulfills online orders Lead(s): Dan Fitzgerald, Steve Smith Other Members: Linda Kwong (wholesale); Steve Smith(online); Dan (Perishables) Mountain Talks Develops program and presents Mountain Talks Lead(s): Mike Brandy Other Members: Steve Smith Native Plant Garden Maintains, repairs and replants native garden at MCVC Lead(s): Carol Lane Other Members: Carole Leadem; Leslie Contreras; Judy Quinlan; Mary Jankowski Nominating Recruits and nominates board members and officers Lead(s): Mark Brauer Other Members: MDIA Executive Committee Outreach Develop and maintain relationships with external partner groups and community Lead(s): Mark Brauer Other Members: Steve Smith Park Maintenance (MVG/TRP) Coordinates with MDSP the repair and improvement of parks structures and the removal of non igneous material from the park Lead(s): Steve Smith Other Members: Dan Fitzgerald Peregrine Team Educate public and monitor the status of the falcons throughout the nesting season. Lead(s): Vacant Other Members: Leslie Contreras, Steve Smith Recruitment Develop a strategy to increase diversity of MDIA board Lead(s): Linda Kwong, Leslis Contreras Other Members: Trail Maintenance Coordinates MDIA sponsored trail maintenance activities and budget Lead(s): Carol Lane Other Members: Trail Signage Coordinates trail sign maintenance and installation with MDSP Lead(s): Steve Smith Other Members: Dan Fitzgerald Volunteers in Park Budget item only: for budget requests from MDSP for VIPP Lead(s): Dan Fitzgerald Other Members: Website and Technology Designs, updates, and maintains the MDIA website assits with technology initiatives Lead(s): Steve Viarengo Other Members: Steve Smith

About Mount Diablo Interpretive Association Who We Are Established in 1974, the Mount Diablo Interpretive Association (MDIA) is a non-profit, all-volunteer organization that assists the California Department of Parks and Recreation in maintaining and interpreting Mount Diablo State Park for its 700,000 visitors each year. Through education, sponsored activities, and publications, MDIA fosters appreciation and the enlightened use of Mount Diablo State Park. MDIA is proud to provide the resources necessary to keep the Summit Museum and Mitchell Canyon Visitor Center open throughout the year. In addition, one of MDIA’s key roles is providing funding to support the Volunteers in Parks Program, which trains and manages park docents, sponsors guided hikes, and helps maintain trails. From left, Front: Leslie Contreras, Tere Dixon, Linda Kwong, Dan Fitzgerald, Carol Lane, Mark Brauer. Back: Mike Brandy, Steve Smith, Dick Nicoll, Julie Braun Martin, Dan Sandri. MDIA is proud to have played a major part in raising funds for the construction of the Museum atop the summit of Mount Diablo. MDIA manages the Mitchell Canyon Visitor Center and is currently raising funds to build a new Education Center at the current site. MDIA Programs and Publications MDIA has a number of programs that are designed to enhance the public's appreciation of the mountain. They range from various educational programs to our trail signage program and the adoption of trails for ongoing maintenance. We sponsor numerous nature hikes throughout the year to aid in visitors' appreciation of the varied features and history of the mountain. The Association publications include the popular Trail Map of Mt. Diablo State Park and various natural history brochures. MDIA offers an e-newsletter providing updates about park events and opportunities to get involved, and prints the Mount Diablo Review for free distribution to park visitors. The Association's first major book was Plants of the East Bay Parks . MDIA's Mount Diablo Guide , published in 2002 by Berkeley Press, is widely available. Mount Diablo: The Extraordinary Life and Landscapes of a California Treasure is a major pictorial publication of the mountain published by MDIA in 2010. Shop Publications Volunteer Opportunities and Membership There are many opportunities for volunteer involvement in MDIA. Anyone interested in volunteering time in support of mountain events, publications, promotional events, or administrative and educational activities is encouraged to contact MDIA for information or visit the Membership page. Education and Advocacy Through its publications and programs, MDIA fosters appreciation for the natural and cultural history of Mount Diablo State Park. MDIA was a major partner in an ambitious plan to create a world class interpretive trail from near the Blackhawk community to the summit of Mount Diablo. With the help of carefully placed interpretive panels, hikers can walk back through 150 million years of geologic history to learn about ancient landscapes, prehistoric animal life, evolving plant forms, and the massive tectonic forces that formed the mountain we know today. Inspiring Future Generations MDIA is leading a campaign to raise $6 million to build a new Education Center in Mitchell Canyon. The new education complex will have ADA-compliant facilities, accommodate school field trips, and provide outdoor education opportunities that are not currently available in the Park. The modern and welcoming education center is designed to inspire future generations to wander the mountain, explore Mount Diablo's biodiversity, wonder at its beauty, and ensure protection. How you can help

Bird Identification Guide Search a bird habitat below or browse full list : Grassland Grassland Shrubland Shrubland Wetland Wetland Woodland Woodland Photo by Kevin Hinsta The photos in this bird identification guide are intended to help you identify the birds that you may see in Mount Diablo State Park throughout the year. The photos were taken by volunteers and include simple descriptions to highlight key identification features. Quicklinks Common Birds A to Z Birds seen All Year Migrating Birds Summer Birds Winter Birds Articles and Resources Introduction to Birding Birds of the Chaparral Peregrine Falcon Red-Tailed Hawk Audubon California Mount Diablo Birds Field Guide : The birds described in this book represent those species that have, at one time or another, been identified as abundant, common or uncommon by observers in the park. Order

Trail Through Time A Journey Through 180 Million Years of Geologic Time Parking access at Rock City, Sunset Picnic Area, Juniper Campground and Lower Summit Parking Lot Introduction With 20 trailside interpretive panels, the complete Trail is 6.25 miles in length with a vertical elevation gain of 2,940 feet. It can also be traversed in reverse down the mountain walking over older to younger rocks. Because the panels are independent of each other, shorter segments of the Trail can also provide an informative geology experience. A Geologic Story Book Like chapters in a book, the rocks of Mount Diablo tell a story of previous landscapes, climates, and life forms as well as epic journeys of tectonic plates. Trail Through Time panels are placed along the trail to help you read the geologic story written in the rocks as you travel through 180 million years of geologic time. Interspersed with the geologic panels are panels on history, geography, and ecology. The Journey Begins Your journey back in time begins near the southern park boundary on Sycamore Creek. As you walk north toward the mountain, you will first journey over 12 million-year-old rocks formed in a shallow sea. Look for shell fossils as you walk. At Rock City, you will pass over 50 million year-old sandstone with unusual erosion features, such as the Wind Caves and Sentinel Rock. You will then cross a rock bed exposing numerous marine snail fossils. When Reptiles Ruled Continue your journey as you cross over the boundary between the “Age of Mammals” into the “Age of Reptiles.” In a short distance you will cross a major fault along which the core rocks of the mountain have been pushed up and over younger rocks. As you continue to climb toward the summit, you pass the former site of a hotel built in the late 1800’s. Walking over Older Rocks As you walk among the varied and oldest rocks of the mountain’s core, you will find contorted red beds of chert made from the skeletons of tiny marine animals, followed closely by an exposure of graywacke sandstone. A short distance ahead is an outcrop of greenstone, an altered submarine volcanic rock. The chert, graywacke, and greenstone rocks have undergone massive compressive forces. The Journey Ends At the end of the Trail Through Time is an overlook to the north with a view over displaced igneous rocks that were originally formed as ocean crust at a distant spreading center. The spectacular view from the summit makes your climb all worthwhile. Download the Trail Thru Time PDF The DEDICATION CEREMONY for the Trail Through Time was held in the Fall of 2008. Work will continue to upgrade the trail alignment and develop outreach programs to encourage public use. We invite suggestions from trail users to help us improve the value of the trail as an educational and hiking experience. California State Parks does not discriminate against individuals with disabilities. Prior to arrival, visitors with disabilities who need assistance should contact the park at the phone number below. To receive information in an alternate format, write to the following address: Mount Diablo State Park 96 Mitchell Canyon Road Clayton, CA 94517 (925) 837-6119 TTY relay service, 711 www.parks.ca.gov Brochure compiled by Mount Diablo Interpretive Association in conjunction with California State Parks, University of California Museum of Paleontology, and the National Natural Landmark Program of the National Park Service. In recognition of the mountain’s importance to our natural landscape, a state park was established in 1931. It was designated a National Natural Landmark by the National Park Service in 1982.

Open: Saturdays and Sundays Mar - Oct hours: 8 am to 4 pm Nov - Feb hours: 9 am to 3 pm See the Park Location page for directions Download: Mitchell Canyon Trail Interpretive Guide (pdf) Learn more about the new Education Center in Mitchell Canyon Mitchell Canyon Visitor Center Mitchell Canyon | Dereck Love The Mitchell Canyon Vis itor Center is located in Mount Diablo State Park at the south end of Mitchell Canyon Road in Clayton, CA. The visitor center is staffed by State Park volunteers and is supported by the Mount Diablo Interpretive Association, whose main goal is to provide visitors with information so they can better enjoy the Park and its natural wonders. The Center has displays about various aspects of Mount Diablo State Park, including geology, wildlife, trails, and plant life. Clothing, souvenirs, interpretive books and pamphlets are for sale. There are also postcards, note cards, trail maps, and water. A docent is on duty when the Center is open to answer questions and to handle sales of materials. The Center also serves as a meeting point for scheduled group hikes and lectures in Mitchell Canyon. We welcome all visitors to join us in the northern part of the State Park. Mitchell Canyon is a Great Place to Hike Oh, the Species You Can See! Mitchell Canyon features varied habitats with a great diversity of plants and animals. This includes uncommon-to-rare species, disjunct populations (populations separated from other populations of the same species, often by great distances), and endemic species (species not found elsewhere). Near the soon-to-be Mitchell Canyon Education Center, Mitchell Creek winds through riparian habitat, chaparral, oak woodland, grassland, and some pine forest. Each of these habitats has its own population of plants and animals that may not be found in the others. Below are highlights of a few fascinating plants and animals that are found along Mitchell Creek. Will you join us in helping to build the new Mount Diablo Education Center, so that for the first time, school buses can safely bring students from any neighborhood in Contra Costa County to experience the mountain? Donate Today! Mount Diablo Globe Lily, aka Mt. Diablo Fairy Lantern (Calochortus pulchellus) DSandri Wide-striped Painted-Dark Bee (Stelis laticincta, Family Megachilidae) DSandri Mitchell Canyon Education Center Entance Mount Diablo Globe Lily, aka Mt. Diablo Fairy Lantern (Calochortus pulchellus) DSandri 1/10

Juniper Campground Map