In 1805, Lewis and Clark saw beaver dams “extending as far up those streams as [we] could discover them.” Even before the famous explorers, French trappers and traders were drawn to the land teeming with beaver.
The beaver is North America’s largest rodent. Its pelt is waterproof and has a double layer of insulation making it highly desirable for human use. At the height of pelt demand, some estimates claim that between 60-400 million animals were taken.
Fortunately, we have beavers living along Deer Creek!
The beaver method of water retention, stream restoration, and habitat rehabilitation.
Beaver ponds and dams;
act as a fire break
slow water movement through a watershed, replenishing the water table, reducing the need for irrigation
filter nitrogen and other chemicals that cause algae blooms resulting in oxygen-deprived dead zones
Ponds volume keeps water temperatures cool, necessary for certain fish species
Discord Between Beavers and People
beaver may eat landscape plants and trees within 165 feet of the water’s edge
water pooling on the land will expand
roads and structures may flood
dams plug culverts and drains
animals and wildlife are attracted to the habitats beavers create
In 2017, the USDA Animal and Plant Health Inspection Service killed 81 beavers in California.
Beaver Problem Remediation
install a pond flow device, limiting water rise, eliminating flooding
choose landscape plants that beaver don’t eat
choose plants that resprout after a beaver visit
keep landscape plants distant from the water source
wrap large trees with 3 ft. high galvanized welded wire fencing or multiple layers of chicken wire
paint tree trunks with sanded paint ( mix 2/3 cup masonry sand per quart of latex paint)
surround groups of trees/ shrubs with 3 ft. high fencing strong enough to withstand a 60 lb animal pushing on it or attempting to get under it
apply and reapply deer and big game repellent
Diet and Behavior
Nocturnal and non-hibernating, beavers eat plants; leaves, bark twigs, trees, willow, cottonwood and other deciduous trees. They’ll also eat garden plants if given the chance.
Pairs may mate for life but are not always monogamous. Kits are born between April and June, remaining with their parents for two years. A beaver colony usually consists of a breeding pair and several generations of their kits.
A full grown beaver can grow up to 60 pounds. (Fossil records show that they once reached 300 lbs!) Their lifespan in the wild is between 5 – 10 years.
Spending most of their time in the water, beavers have few predators. When on land, they are most vulnerable. Predators include; man, wolves, coyote, mountain lion, bears, bobcats, and dogs.
The Beaver Butt Thing – Castoreum
Aside from fur, trappers learned of another beaver special quality; castor glands, located near the anus, smell vanilla sweet. Castoreum is secreted with urine to mark territory. One can’t help imagining the very first gland discovery. A mountain man noticed it while taking the animal apart. To verify, he needed a close-and-personal secondary sensory test. Enthusiastic conversations between trappers spread the news and began a new industry.
Castoreum, a thick, syrup-like ooze was used in the perfume industry, starting in the 1800’s, to enhance other scents and increase their longevity.
“The United States, the Food and Drug Administration lists castoreum extract as a generally recognized safe (GRAS) food additive. … While it is mainly used in foods and beverages as part of a substitute vanilla flavor, it is less commonly used as a part of a raspberry or strawberry flavoring.” Wikipedia
Despite Castoreum’s listing with the FDA, it was never a substance in wide use. Anesthetizing and milking beavers was time-consuming and costly.
[Castoreum should not be confused with Castor, as in Castor Oil, which is a plant.]
continuously growing incisors
an insatiable need to build at the sound of water
tail functions as extra leg while on land
a mouth valve that keeps water out while carrying/floating a tree or branch
ear valves with the same function
back of throat valve – ditto
nostril valves – ditto
nictitating membrane covers eyes underwater acting like goggles
tail slaps on water warn of danger
hind foot has a split toenail used as a comb
fur is waterproof, treated with an oily substance
intestinal bacteria ferment cellulose to digest plant matter — this is why castoreum smells so good!
California Native & Aquatic Keystone Species
The National Geographic Society describes a keystone species as an organism that helps define an entire ecosystem. Without its keystone species, the ecosystem would be dramatically different or cease to exist altogether.
The lone howl, the most recognized coyote vocalization, is thought to be a proclamation by an individual coyote separated from its pack.
Contact & Greeting – ‘Wow-oo-wow’ appears to be a “greeting song” when two or more pack members reunite. Group yips are thought to be a response to the lone howl.
The coyote is North America’s oldest indigenous species
Originating near Yellowstone three million years ago, this medium-sized canine is extremely adaptable and intelligent. They’ve settled into every wild, rural and urban corner of the North American continent.
Unlike other species that were extinguished by eradication efforts, Coyotes create replacement populations when their numbers are reduced.
Coyote experts suggest that it’s easier to train coyotes and people to coexist rather than launching hunting campaigns. Killing coyotes opens more territory for roaming individuals to claim.
Breeding season is February through March. Coyotes are monogamous and mate for life.
In spring, newly mated couples claim territories and set-up dens. Den establishment may be cleaning out a previously used space or taking over an abandoned skunk, badger, or marmot holes.
A pregnancy lasts about two months. Litters range be between 3 – 12 pups. Litter size is determined by the number of other coyotes in the territory and the availability of food.
Once the cubs are born, the male and other pack members help feed, raise and protect them. Pups remain with the parents somewhere between six months to one year.
The Pack & Social Behavior
A family unit contains a reproductive female and her mate. Nonreproductive females, bachelor males, and other young adults may join the pack in the winter for companionship, but this is usually temporary.
Hunting coyotes can be singular or work in groups. At times pairs and small packs will form to take large prey such as deer, cow, sheep, or large domestic dog. (The ever-unpredictable coyote may also initiate play behavior with large pet dogs.)
Occasionally, coyotes will form interspecies relationships. Coyotes have been observed working in tandem with American badgers while rodent hunting. A badger has been seen allowing head snuggles and face licking from a coyote.
Aggressive coyote behavior most closely matches fox behavior.
While not common, coyotes have been known to breed with dogs when there is no other alternative.
Statistics & Threats
Males = 18 – 44 lbs
Females = 15 – 40 lbs
Life span 6-8 years.
Humans pose the biggest threat to coyotes. In rural farming areas, most coyote deaths are caused by hunting and trapping. In urban environments, the majority of coyote deaths are caused by automobiles.
90% of a coyote’s diet consists of meat, but a coyote will eat almost anything, often experimenting with previously unknown items.
snakes (Rattlesnakes! Coyotes tease the snake to uncoil, then bites the head and shakes.)
black bear cubs (unusual)
also scavenges large animal carcasses
In wild areas, coyotes may compete with bobcats and mountain lions for mule deer.
Scavenging in Rural & Urban Areas
If fresh meat is not available, coyotes will scavenge for;
dropped fruit under fruit trees
Winter Food Sources
In winter they will also eat;
other animal droppings
Cities and Populated Areas
In urban areas, a coyote diet can consist of;
dog and cat food
feral cat populations
bird seed at feeding stations
large dogs (sometimes), with several coyotes working as a team
Coyotes in cities should be wary of humans.
It’s up to people to reinforce the coyote’s fear
Hazing will help maintain healthy boundaries for all.
blowing an air horn
spraying it with a water hose
or acting aggressively
looking at it directly in the eye
make yourself look larger
motion sensitive outdoor lighting may discourage coyotes
In areas where livestock is at risk, some ranchers and farmers have found that llamas, donkeys, and dogs bred for guarding aid as coyote deterrents. (See University of California – How to Manage Pests link below for details.)
Identifying Problem Behavior
Increased numbers of coyotes on streets and in yards
Hunting pets in the daytime
Coyotes seen in playgrounds or parks during the day
Coyotes approaching people during the daytime and/or behaving with aggression
Chasing joggers, bicyclists or other outdoor enthusiasts
Attacking pets while the pet is on a leash
When a Coyote Becomes a Safety Hazard
A coyote becomes a public safety hazard when it no longer fears humans and behaves with aggression.
Coyotes that bite humans have usually been fed by humans
In 2017, the USDA Animal and Plant Inspection Service killed 3,199 coyotes in California.
If a coyote has developed bad behavior, a predator removal professional must be called (it is illegal to shoot firearms in populated areas). Coyote relocation is not an option, the animal is killed. Nevada County’s Federal Trapper can be reached at 530-470-2690 during office hours.
With their ability to predict outcomes, make changes, communicate, quickly identify new food sources and understand human behavior, it’s easy to see why the coyote is an evolutionary success story.
In Nevada County, and along Deer Creek, it’s important to realize that coyotes are always watching. Just like discouraging bad bear behavior, residents must be vigilant about keeping food and water sources at a minimum. It’s also wise to mindful about creating situations where small pets and farm animals may become prey.
If humans do their part by keeping coyotes wary, the two species can coexist peacefully. Haunting coyote song will serenade us at night and they’ll keep our rodents, insects and rattlesnakes in check.
At age 43, after being sick with consumption, Alonzo Delano left his home and loved ones to join the mass of gold-seeking emigrants making the overland journey to California (1849). In Illinois, he sold bank stocks and commodities and lived with his wife and two children; Fred an invalid son of 16 and Harriet, a six-year-old daughter.
After surviving the laborious trek and multiple attempts at gold mining, Alonzo settled in Grass Valley where he invested in a quartz mine and returned to banking and selling merchandise.
Drought & Fire 1854 & 1855
In 1855 two events occurred that caused great upset for the people of Grass Valley, allowing Delano to demonstrate compassionate leadership and his ability to focus a dispirited community on a hopeful future.
A drought in 1854 limited water availability. Mines struggled to keep working and miners couldn’t pay their debts. Real estate prices crashed. The nation’s leading bank (not Wells Fargo) made an investment in a railroad that failed.
Alonzo was the Wells Fargo agent in Grass Valley. When communication from San Francisco reached him about a bank run, he opened the Wells Fargo doors on time. Climbing on top of the service counter, he declared to all, “Come on. I will pay out to the last dollar, and if that’s not enough, my own property will go.”
A month later Delano was elected the first Treasurer of Grass Valley.
Seven months went by before the second disaster struck. A terrible fire leveled at least 300 buildings, leaving thousands homeless.
“Give my love to all my friends. Tell them I was not afraid to die, and that I left the earth without ill feeling toward anybody,” Alonzo made this deathbed appeal to his wife.
“Old Block was a courageous pioneer. He loved and inspired his fellow men,” said Ezra Dane – Gold Rush writer & San Francisco Lawyer (1904-1941)
Delano’s 1849 Journal Entries Published in a Book
Traveling somewhere between 15 – 20 miles per day, the overland journey took five months. At dinnertime, Alonzo journaled about the events of his day. Sickness, starvation, thirst, and death became common experiences. Delano’s keen observations provide a window in time that shows travel conditions, food, finding water, wild animals, Indians, and the open expanse of the Sacramento Valley.
Below are selected excerpts from Life on the Plains and Among the Diggings [1849 – 1854] as well as additional Delano writings that give the reader a 318° view of Gold Rush life and early California and Nevada County.
Sickness and Bad Food
April 5th, 1849
…since the invasion of Rome by the Goths, such a deluge of mortals had not been witnessed, as now pouring from the States to the various points of departure for the golden shores of California.
On the second day [aboard steamer Revolution at St. Joseph, Missouri], amid the gaieties of our motley crowd, a voice was heard, which at once checked the sound of mirth, and struck with alarm the stoutest heart — “the cholera is on board!”
We discovered that we had been imposed upon in St. Louis in the purchase of our bacon, for it began to exhibit more signs of life than we had bargained for. It became necessary to scrape and smoke it, in order to get rid of its tendency to walk in insect form.
I did not wonder that the aborigines were attached to their delightful country, and had it been mine, I should have defended my possessions against the encroachment of any lawless intruder.
I learned that three miles beyond there was a spring. It was nearly sunset when I again entered the deep wood, but my anxiety to get in sight of the abodes of civilized man impelled me forward, choosing to risk a night alone in the woods, among the wild beasts which swarmed in that region, rather than not gain the distance.
First Sight of Sacramento Valley
Ascending to the top of an inclined plane, the long-wished-for and welcome valley of the Sacramento, lay before me, five or six miles distant. How my heart bounded at the view! How every nerve thrilled at the sight! It looked like a grateful haven to the tempest-tossed mariner, and with long strides, regardless of the weariness of my limbs, I plodded on, anxious to set foot upon level ground beyond the barren, mountain desert.
In addition to other calamities, many suffered from scurvy and fevers – the consequence of using so much salt or impure provisions, and while many others died, others were made cripples for life.
Photo Credit: B.D’s world
By the earliest arrivals, in June and July, of those emigrants who reached the valley, the sufferings and destitution of those behind were made known, and the government and individuals once more extended the hand of relief. San Francisco, Sacramento City, and Marysville made large contributions, and trains loaded with provisions were dispatched to meet them.
In addition to this, traders pushed their way over the snows to Carson’s Creek, and Truckee River and even to the Sink of the Humbolt, with supplies; and although much good was done, and many lives saved, yet aid could not be rendered to all.
It was found, too, that talent for business, literary and scientific acquirements, availed little or nothing in a country where strength of muscle was required to raise heavy rocks and dig deep pits.
California proved to be a leveler of pride, and everything like aristocracy of employment; indeed, the tables seemed to be turned, for those who labored hard in a business that compared with digging wells and canals at home, and fared worse than the Irish laborer, were those who made the most money in mining.
And here I found myself more than two thousand miles from home, in a city which had risen as if by enchantment since I had crossed the Missouri.
Camping Near Bear River
…spreading our blankets, [we] were soon asleep, despite that howling of the cayotes all around us.
Coyotes & Dogs Frolic
These animals are of the dog species, and appear to be connecting link between the fox and wolf. They frequently go in packs, but rarely attack a man, unless pressed by hunger, which is not often, for the number of horses and carcasses of wild cattle in the valley furnish them food, and they are not looked upon as dangerous. I have seen them stop and play with dogs, which had been set upon them, returning their caresses, and showing no disposition to fight.
I was soon looked upon as a friend, and for aught, I know recognized as of the tribe of Oleepa. … among themselves, and with those whom they confide, a more jolly, laughter-loving, carless and good-natured people, do not exist. The air resounded with their merry shouts as we sat around their fires at night when some practical joke was perpetrated, or a funny allusion made. And they were always ready to dance or sing at the slightest intimations, and nothing seemed to give them more pleasure than to have me join in their reactions. To each other, they were uniformly kind, and during the whole of my residence with them, I never saw a quarrel or serious disagreement.
Dwindling Indian Population
…They are already dwindling, for the fire-water and rifle of the white man are doing their work of death, and five years will not pass ere they will become humbled and powerless – a wretched remnant of a large population.
Photo Credit: Brian C. Stanford
Grizzly Bear in the Sutter Buttes – a Daughter Saves Her Father
About twelve miles nearly west of us, a solitary butte rises from the plain, from fifteen hundred to two thousand feet high, and whose broken, craggy and pointed ridges seem to kiss the clouds. It stands nearly in the center of the plain, equi-distant from the coast range and the Sierra Nevada.
…setting his rife against the rock, he [Peter] climbed over the ledge, when, to his horror he found himself facing a huge grizzly bear. The monster sprang upon him at once…tearing his scalp from his head, and biting him in a fearful manner… they both fell off the rock, and rolled down the hill. Peter, in the meantime, making the best use of his knife possible, inflicting several severe wounds upon his adversary.
…with the impulse of one inspired, [Peter’s second daughter] sprang towards her father…and with unerring aim, discharged it at the bear. The bullet took effect in the monster’s head, and he fell, stunned if not dead. Instantly she ran and seized her sister’s rifle, and returning placed it against the bear’s ear, and what little life remained soon passed away.
Engineering Water Movement
Where water is not found in isolated places, canals are dug, sometimes forty or fifty miles long, by which water is carried from some permanent stream along stupendous hill-sides, over ravines and gulches, and around rocks by sluices and flumes, often at vast expense of labor and money – thus arresting the skill, energy, and enterprise of the people who are delving among the mountains; hoping to acquire a competence to smooth the down-hill of life, and render old age comfortable.
Lumber; the New Riches
In the mountains, water-power is abundant for all mechanical purposes, and the noble pines, made into lumber, will form a source of wealth equaled only by its mineral treasures.
Hard Work & Failure; the Fickleness of Finding Gold
Were the personal adventures of a moiety of the emigration of 1850 to be written, they would furnish a volume of absorbing interest, forming a sad commentary on the California gold-seeking mania, which produced more wide-spread misery than any similar occurrence in the annals of mankind.
I do not hesitate to declare that no one should emigrate, unless with the intention of making it [California] his home for life.
Gold Rush Climax
The country is large enough and productive enough to support a dense population, and individual suffering would be less if it was filled up by degrees; but one great difficulty is too many are rushing in at once before the way is sufficiently prepared for them. Now a limited number can cross the plains safely and with comfort if properly provided, but this year there are too many going at once. In addition to the stick actually required to draw the wagons on the road, a large number of cattle are being driven for market. The will generally reach the Rocky Mountains in safety – that is, there will be grass enough to sustain the cattle. But immediately on going through the South Pass the desert country commences, grass will be difficult to obtain and, I believe, impossible for so great a number. The consequences will be that the cattle of emigrant trains will die, and families will have a terra firma shipwreck, hundreds of miles from human aid. If they have money to duplicate their teams from droves, they may be partially relieved; but very many will not be able to pay the California prices which will be asked, and they will be left to get along the best way they can, which will be on foot, or die. – True Delta – June 23, 1852
Delano – a Prolific, Eloquent Gold Rush Writer
“We have pleasure in publishing … one of the ablest correspondents it was our good fortune to secure in California in the early days of the gold discoveries. His letters to this paper were graphic, truthful, eloquent and patriotic, overflowing with generous sentiment and the spirit of manly independence so characteristic of the sons of the glorious West.” True Delta, August 12, 1852
While living in California, Delano was a correspondent for the San Francisco Daily Courier, the Pacific News, The Union, the California Farmer, the Golden Era, the Telegraph, the Hesperian, and Hutchins’ California Magazine. His work also appeared Edwin F. Beans’s History and Directory of Nevada County and the New York Times.
Life on the Plains and in the Diggings Book Review
In a time when we have plentiful water at the turn of a tap, instant worldwide communication, refrigeration, food safety, health care and emergency services, shelter from weather, planes, trains, and highway systems, it’s good to be reminded of the luxury they represent. It’s valuable to imagine the hardships endured by the brave (or foolish!) folks who adventured to a remote and distant land in covered wagons and on foot.
The level of detail in Delano’s writing is thrilling and mesmerizing, almost like walking the trail beside him.
Pinus Sabiniana is native to California and Oregon and has a variety of names.
Its habitat forms a ring around California’s ‘bathtub’ (central valley). It grows in poor soils, is adapted to hot, dry summers and usually keeps company with Blue and Live Oaks.
Common Names & Naming History
Common names include;
California Foothill Pine
Sabines Pine and
Sabine Nut Pine
In published writings before the 1800’s, the tree was known as Digger Pine. According to Erwin Gudde author of California Place Names: The Origin and Etymology of Current Geographical Names. “…the name seems to have been used in a geographical sense mainly in Wintu territory. With these tribes, roots are, for the great portion of the year, their main subsistence.” (Schoolcraft, Archives of aboriginal knowledge, 1860). The diggers also valued as food the green cones and the seeds of the Pinus sabiniana, whence the common designation Digger Pine.”
Like monuments and other articles of history, once the full story is understood, it often sheds light on derogatory designations and attitudes. Such is the case with the name Digger. For valid reasons, the Pinus Sabiniana has many other common names to choose from.
Cones, Nuts & Resin
Current tree distribution may be a result of human cultivation. Native populations are known to have tended to plants used for food, clearing brush and redistributing seeds.
Gray pine nuts are also important food sources for the California gray squirrel, acorn woodpeckers, rodents, and a variety of birds. The Scrub and Steller’s jay eat the seeds and move them, assisting with tree migration and reproduction.
Highly Flammable Tree
Gray pine is a prolific resin producer. The bark, cones, wood and needle sheaths contain pitch. This makes the tree vulnerable to fire damage.
Adaptations that aid in fire survival are; thick bark on mature trees and low branch self-pruning. Additionally, Gray pine seeds regenerate following fire.
“…this tree looks more like a palm than a pine,” writes John Muir in My First Summer in the Sierra. “Sabine pine (Pinus Sabiniana), which here forms small groves or is scattered among the blue oaks. The trunk divides at a height of fifteen or twenty feet into two or more stems, out-leaning or nearly upright, with many straggling branches and long gray needles, casting but little shade.”
Western Dwarf Mistletoe – Arceuthobium occidentale
Dwarf mistletoe observations in Gray Pine trees off Newtown Rd.
Though mistletoes are parasitic and pose a serious threat for forest product trees, it is a valuable part of Life on the Creek. Insects, birds and small mammals consume parts of the mistletoe. In some tree species, the parasite causes the formation of witches brooms, dense outgrowths surrounded by foliage. This provides a safe haven for bird nests and other small creatures.
“History, warts and all,” is the essence of what Gary Noy delivers. Noy’s meticulous research, ferreting through dusty archive boxes for photos and first-person accounts, makes his gritty, sometimes enormously disturbing, and often entertaining Gold Rush story vignettes radiate with life.
In the lawless immigrant melting pot of California dreams, “accidents, disease, murder, natural disasters, [and] mob violence, … took a heavy toll during the era. Some estimates indicate 20 percent of all forty-niners died within six months of reaching California,” Noy writes.
From the extinction of California’s Grizzly Bear, environmental destruction, and racist atrocities to situations engendering multi-cultural cooperation, Noy links California’s haunting past to contemporary issues still playing out today.
Most rivers in California have been changed by mining, water control, and the introduction of new species. Professor Erika Zavaleta of UC Santa Cruz explains the history and biology of California’s watersheds. She also presents current watershed management issues.
In Nevada County, we are mostly unaware of the small solitary wild cats that control rodent populations.
Their stumpy tails inspired the common name – bobcat. Rufus, the scientific species name, is derived from its brown coat.
Bobcats are adaptable. They live in deserts, forests, and urban areas throughout North America. They live as far south as Northern Mexico and as far north as Southern Canada.
Photo Credit: Richard Mooney
In California, home ranges (territories) vary between 1/4 to 1/2 square miles. The range of a male is twice the size of the female. Male territories may overlap. Female home ranges do not.
Bobcats will select home ranges based on food availability, cover, protection from elements and human activity. Farms and recently logged areas attract prey animals; bobcats naturally follow.
Obligate Carnivores, bobcats only eat meat. Their diet consists of; rabbits, mice, ground squirrels, woodrats, and gophers. They have also been known to eat birds, lizards, insects, and deer if a carcass is available. Bobcat prey usually weighs between 1 1/2 to 12 pounds.
Photo Credit Linda Tanner
Opportunists, they are adaptable to living in urban environments. If their territory encompasses farm animals, they will prey on lambs, chickens and young pigs.
The California Department of Fish and Wildlife stresses, “that aggressive behavior by bobcats toward humans is extremely rare. Most bobcats are elusive in nature and rarely seen.”
Solitary creatures, they avoid human contact. Bobcats are most active between dusk and dawn and hunt in open grassy areas.
Females will have between 2-4 kittens per litter. They give birth between February and June.
The bobcat mother raises her offspring alone. Natal den sites are located in thick vegetation, hollow logs, inside abandoned woodrat nests, or within rock outcroppings – any place the female feels is concealed and safe for her young. Several additional shelter dens inside her home range can be in stumps, brush piles and on rock ledges.
Owls, foxes, coyote, mountain lion, adult male bobcats, and humans are predators of bobcat kittens. When the kittens are between 8 – 11 months old, they are forced out to find territories of their own.
The average lifespan for a bobcat is approximately 5 years, but some study subjects have made it to 15 years.
Exposure to Disease & Toxins
Just like house cats, bobcats are susceptible to the same diseases. Both types of cat can transmit pathogens to each other.
Newtown Rd. bobcat with an engorged tick. Photo Credit: Terry & Anita Hansen
The most dangerous environmental threat to bobcats is rat poison. With affected mothers, bobcats can have life-long exposure.
The story of Deer Creek begins with the formation of the continent. It was during this phase of geologic time that gold was created.
About 160 million years ago, the ocean floor of the Farallon oceanic plate began sinking below the North American Plate. Tremendous subduction forces heated and drove mineral-rich water through cracks where the two land masses folded. Gold and other minerals cooled in the Smartville Complex, the heart of the Gold Rush in the Sierra Nevada Mountains.
Donner Summit rides at the top of the Smartville batholith, a twenty-five thousand square mile section of solid granite that is mostly under the surface of the Sierra Nevada Mountains.
Geological Society of America Abstract
The Smartville Complex comprises a north-trending submarine intrusive-extrusive (ophiolitic) complex, approximately 100km long by 40km wide in the northwestern Sierra Nevada Foothills. Generally, from bottom to top, rocks comprise serpentinite (a few exposures), olivine gabbro, and layered gabbro, varitextured massive pyroxene and hornblende gabbro, plagiogranite, massive diabase, sheeted diabase, pillow lava, and volcaniclastic sediments. A few massive sulfide deposits are present in the volcaniclastic sediments. Rocks range from nearly undeformed–perhaps the best-preserved sheeted dikes and pillow lavas in North America–to highly schistose. Structure is complex, but rocks describe approximately a north-trending antiform that structurally overlies mélange and associated sediments of the Central Belt of the Sierra Nevada. Dikes intrude both igneous rocks and here and there Central Belt sedimentary rocks. Dikes are mostly north-trending, but curve to NE-trending towards the N. In places (Stanfield Hill, Marysville Road) the dikes are nearly undeformed, trending NNW and dipping steeply E. In other places, e.g. in Auburn, Oroville Dam south abutment, and along the E. side of the complex, dikes and other rocks are highly foliated.
Volcanic rocks compositionally are mostly island-arc tholeiites and oceanic andesites, although MORB compositions have been reported in a few places. Tectonic relations with underlying rocks include a tectonic window near Higgins Corner, a half-window north of Lake Oroville and the high-angle Wolf Creek Fault zone and continuations on the eastern side. On the west, the Smartville and associated rocks are covered by Great Valley deposits and/or intruded by subsequent granitic plutons. Associated ophiolitic rocks include the older Lake Combie Complex, east of SR 49, and the approximately 200 Ma Jarbo Gap and Slate Creek Complexes N and NE of the Smartville complex.
The Smartville complex and associated ophiolites may have been emplaced by collision of one or more west-dipping subduction zones with the North American Continental Margin (or with the western margin of the “Rubia” ribbon continent” of Hildebrand, 2009 GSA Sp. Pap. 457.
Rock & Mineral Identification
Following is part of an Introduction to Physical Geology video course from the City College of San Francisco (Katryn Wiese). Videos below discuss how to identify minerals (formed by organic debris or volcanic glass) igneous (formed by lava), sedimentary (formed by compaction), and metamorphic (formed by pressure & temperature) rocks.