We’re approaching mid-January, the time of year when the Following Deer Creek (FDC) Project first came into being (2017). Like the Earth circling around the Sun and the planetary water cycle, we’ve completed a journey.
I set out to tell the story of the Deer Creek watershed from its tectonic and cultural origins to the people and animals who live in it today. Working backward, I posted blog articles as I researched in preparation to compile the film.
In early January of 2021, the film was complete. Like the FDC blog posts, it’s a birds-eye view of the watershed that hints at depths.
I smile when I think back to the initial idea seed. Of course, there is no one story, there are more than can ever be told.
FDC and the Aerial Views film is a decent outline, but it also illustrates how much more remains for investigation and study.
“NEVADA CITY, CAL – Cotton Bros. & Co, Oakland, CAL were awarded a contract April 14 by the county supervisors for constructing the following bridges; steel bridge over Deer Creek, $2,248.” – Engineering News and American Railway Journal, Volume 39, April 28, 1898, pg. 145
“The Cotton Brothers and Company was an important California based bridge builder of metal truss bridges in the late nineteenth century and early twentieth century. They built several bridges in Nevada County during the 1890’s, including the Purdon Bridge.” – Historic American Building Survey, National Park Service – Wolf Creek Bridge PDF
Crayfish are freshwater crustaceans related to shrimp, lobster, and crabs. They’re all decapods—having ten legs.
According to the U.S. Geological Survey, the native range for the Signal crayfish (Pacifastacus leniusculus) is the Columbia River’s lower estuary. The range goes northwest and through tributaries that reach into British Columbia, Washington, Idaho, and Oregon.
Historical records say crayfish were first introduced to the Truckee River and Lake Tahoe sometime between 1895 and 1909. They were placed there for fish food, bait, and human consumption. Crayfish are currently planted in ponds and on fish farms to control aquatic weeds.
Crayfish live in a variety of freshwater environments from backwater pools to large rivers, streams. and subalpine lakes. Favorite places include hiding among rocks and in stands of partially submerged plants. They are temperature and pH-sensitive.
Anything and everything…
rotting leaves and twigs
animals and insects (younger crayfish are most attracted to these)
live plants and algae (older crayfish are most attracted to these)
other crayfish (large crayfish are most likely to cannibalize other crayfish)
Crayfish breathe through gills. They can survive on land as long as gills remain moist. In water, gills also collect small food particles.
Most activity and feeding occurs at night.
Crayfish have two sets of antennae, one set for touch and the other for smell.
Body armor—or the exoskeleton—is a crayfish’s main defense, though pincers are also used for battle.
The exoskeleton is made up of calcium carbonate (limestone), taken from the water. It builds up in layers. When the animal grows, it sheds its exoskeleton. At this time, it is at its most vulnerable until the new exoskeleton hardens.
Molting occurs most often as young grow to adulthood. Once crayfish are fully grown molting only happens a few times per year.
Crayfish have the ability to regrow claws if they are lost. Claws are also used for eating and mating.
Depending on food availability and water temperature, breeding can begin between three to six months of age. Mating usually occurs in the spring and summer months.
Mothers can hold sperm until conditions for egg-laying are right, usually in fall.
Females lay somewhere between 200 – 400 eggs. These are attached to her swimmerets under her tail. Young remain with their mother through several molts. As they grow, they separate somewhat, staying attached by thread-like tethers. Once fully separated, the mother secretes a pheromone that keeps the young close for protection.
Average is about 3 years. In captivity, some have lived up to twenty years.
Anything living in or near the water.
Crayfish Consumption in the West:
Washington, Oregon, and the Sacramento Delta are the main crayfish food consuming areas on the west coast. According to the California Department of Fish and Wildlife, over ten-thousand pounds of Signal Crayfish were taken out of the Sacramento Delta in 2018.
Dangers to Crayfish:
oil or fuel
changing land use activities that alter water flows
Crayfish Species Where They Don’t Belong (Shipping Crayfish to Classrooms):
Carriers of a Plague Organism:
According to the U.S. Fish and Wildlife Service, “crayfish plague, caused by the fungus-like organism Aphanomyces astaci Schikora, is listed in the top 100 of the “World’s Worst” invaders by the International Union for Conservation of Nature.”
Like the Asian Ladybug, Signal crayfish can live in a balanced host-parasitic relationship. If they are brought into places where that balance hasn’t been established, ecosystem havoc can result.
California Department of Fish and Wildlife Recommends Eating Some Invasive Species
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.