As you look out into the surrounding hills of Malakoff Diggins, you will see a heavily eroded landscape that was once representative of a mountain range developed from sedimentary and volcanic rocks of the Paleozoic age. This mountain range eroded rapidly when the bedding plane tilted westward when granite plutons* lying to the east were tilted upward during the late Pliocene and continued through the Quarternary period. This uplifting occurred between one million and five million years ago. During this period, the drainage system of rivers that had previously flattened the landscape cut deep perpendicular gorges, bringing the present configuration of rolling hills on flattened ridges dissected by steep-walled canyons 300 – 1,000 feet deep.
*A pluton is an intrusive igneous rock body, typically kilometers in dimension, that crystallized from magma slowly cooling below the earth surface. The most common rock types in plutons are granite, granodiorite, tonalite, and quartz diorite.
Malakoff Diggins is representative of the “Auriferous Gravels” deposited by the wide ancestral Yuba River that ran through the area prior to the uplifting of the bedding plane. When the Sierra Nevada Mountains were formed, this ancient river channel which held the gold-bearing gravel became dry. After million of years of erosion, these gravel beds became buried.
Much of the rock in these gravel beds was quartz. When the earth was forming and magma was extruded from deep within the earth core, the mineral gold in its liquid state filled the fissures and cracks of the quartz rock. When the quartz rock became closer to the earth’s surface, the gold hardened. Erosion over the millions of years broke the quartz rocks, freeing the “placer” gold.
Hydraulic mining exposed the different layers of the ancient gravel beds. What you see today in the cliff walls along the Diggins Loop Trail are the many layers of sedimentary rocks and gravels. The red color on the walls is from iron oxide. When the mineral iron is exposed to air it turns red.
The region we are in is representative of needle-leaf “Sierra Yellow Pine” and “Sierra Montane” forests. The area consists of dense conifers, including ponderosa pine, white fir, sugar pine, and incense cedar as well as black oak, live oak, and big leaf maple. The shrubs consist of manzanita and buck brush (ceanothus.) Ground cover is dominated by annual grasses and bear clover (mountain misery.)
Black tail and mule deer populate the region. The largest carnivore is the american black bear. The grizzly bear has been extinct in California since the late 1920’s. Smaller mammals consist of mountain lion, bobcat, coyote, and grey fox. Ring tail cats are occasionally seen. The last recorded porcupine sighting in the park was in 1996. Grey and ground squirrels, douglas squirrels (chickaree), cottontail and jackrabbits are common. Both mountain and valley quail are present, as are the non-native turkey.