Table Mountains, California
Published: June 11, 2014, 2:12 pm
Author: C Michael Hogan (Table Mountains, California)
The Table Mountains of California lie at the eastern verge of the California Central Valley with the foothill slopes of the Sierra Nevada Mountains rising in successive ridges to their east. The Table Mountain Range is floristically noted as one of the few extant refugia for the once vast native grasslands of Central California. Unlike most of this original native grassland expanse, whose character was substantially altered beginning in the mid nineteenth century with waves of European settlers and gold prospectors, parts of the Table Mountain Range is substantially ecologically intact. This intact portion within the Table Mountains is often simply termed Table Mountain, designating the prominent northern mesa within Butte County; this landform element is the best known venue for the elaborate spring wildflower profusion that draws numerous visitors each year. Certain maps depict this feature within the northern extent as the Northern Table Mountains, while the lower elevation southerly part of the range is termed the Southern Table Mountains.
The Table Mountains addressed in this article specifically address the landform in Butte County, California; however, in the historical geological literature Table mountains is a term that has been applied to a number of similar formations lying along the western edge of the Sierra Nevada.[1]
Geology and hydrology
The formation of the Table Mountains is linked to mid- to late-Jurassic Period collisions of the Continental Plate and an island-arc plate, whose collision and ensuing subduction resulted in tectonic uplift forming the Sierra Nevada batholith. Approximately 65 million years ago a gravel riverbed flowed below what is the present day Table Mountains west of the ancient plate collision boundary. The overlying material of the Table Mountains derives from one of the Lovejoy volcanic flows, which buried the river bed in an era between 14 and 24 million years before present. [2]. Subsequent eroding of the soft sides of that ancient river channel left the basalt cap much as it now exists, as a relatively flat-topped mesa formation.
There are no perennial streams within the Table Mountains due to the minimal aquifer formations and the lack of runoff in the dry summer season. Seasonal streams, including waterfall elements, are found deeply incising the basaltic cap; moreover, seasonal ponding or vernal pools are found atop the generally flattish top of the Table Mountains landform.
Flora
The vascular plants of the Table Mountains represent high biodiversity [3]and one of the important elements of the California Floristic Province. The array of vegetative species found here are, in many cases, a microcosm and relict of the original expanses of native grasslands of the California Central Valley. The noted floristic diversity is particularly evident on Table Mountain, an iconic butte formation within the northern Table Mountains. Here the thin soils and abundance of diverse micro-habitats form the basis for the inherent diversity of forbs and grasses (Grassland biome).
Dominant trees and shrubs of the Table Mountains include a number of oaks, including Interior live oak, Quercus wislizenii, Blue oak, Quercus douglasii [4] and Valley Oak, Quercus lobata onthe more open slopes; California black oak, Quercus kelloggii, and Canyon live oak, Quercus chrysolepis are also present, particularly in the more sheltered ravines and mesic slopes. Two pines are interleaved among the oaks, with Grey Pine, Pinus sabiniana, commencing on lower elevation slopes and Ponderosa pine, Pinus ponderosa, blending in the higher elevations. Understory shrub species on sunnier exposures include numerous manzanitas such as Big Manzanita, Arctostaphylos manzanita, and White-leaved manzanita, Arctostaphylos viscida. In the denser wooded stands and more mesic locations are found Toyon, Heteromeles arbutifolia and California bay, Umbellularia californica.
The micro-habitats of the Table Mountains were first described in detail by Jim Jokerst. [5] The chief such micro-habitats include bedrock flat-tops, bedrock edges, fractured basaltic cobbles, cobble piles, basaltic cliff faces, frost polygon mounds, thin soils, thicker soils and moist forested areas. Aqueous habitat areas include riparian zones and vernal pools.
On the basaltic flat-top areas there are forbs such as Volcanic onion, Allium punctum, and Dwarf stonecrop, Parvisedum pumilum. Along bedrock edges are found one of the most prolific wildflowers of the the butte top, California goldfields, Lasthenia californica. At locations of fractured basalt, typically large dry broken parts of cooling columns, one finds such hardy plants as Kaweah River phacelia, Phacelia egena and Zigzag larkspur, Delphinium patens.The cliff faces are often seasonally seeping and reminescent of the hanging garden habitat of the somewhat distant Colorado Plateau; here are found such forbs as Red larkspur, Delphinium nudicaule and Rebecca Aistin's rockcress, Arabis brewerii var austinae.
History
The ancient riverbed gravels contained relatively high concentrations of gold ore, which mineral was discovered on Table Mountain in 1853 by a teacher/prospector named Sol Potter working with his Cherokee pupils. The present day hamlet of Cherokee is situated at the vicinity of the gold discovery site. Diamonds were also produced in some of the gold bearing deposits, but gold extraction was limited due to the lack of surface water flow on the Table Mountains. In 1870 a major diversion of the Feather River was created to establish hydraulic mining, an activity that created a surge of ore production, although the method was outlawed by 1887, after the community of Cherokee had reached a population in excess of 1200 people. [6]
The biological exploration of this region includes remarks by John Muir that the wildflowers of this area exhibit one of the greatest floral color displays and biodiversity of any place he had ever visited; of course, in Muir's era, the expanse of native grasslands was an enormous extent across the Central Valley as well as the valley fringe at the Table Mountains. William H. Brewer may have been the first to detail the geology of the Table Mountains and deduce their formation from lava flows over the ancient gravel river bed. [[[7]]] Modern biological exploration featured the work of Jokerst and others to amplify the rich detail of this landscape at the Table Mountains.
Conservation
The lower western slopes of the Table Mountains are severely degraded by past conversion of forested lands and native grasslands for intensive agricultural use, especially grazing. In many cases these slopes are overgrazed, resulting in denuding of vegetation, propagation of weedy non-native grasses, soil erosion and land slumping. The higher slopes of Table Mountains have a better preserved wooded character, punctuated with refugia of grassland relicts that comprise one of the richest enclaves of native flora in northeastern California. These areas have survived non because of human protection, but due to the harshness of the rocky landscape that is inhospitable to many forms of human exploitation and is also not friendly to the non-native species that have effectively taken over the more fertile deeper soils of the California Central Valley floor.
Through efforts of the California Native Plant Society and other conservation groups, the Table Mountain flora has been extensively studied for their species richness, biodiversity and varied micro-habitats. The relative remoteness and paucity of other visitor attractions have been instrumental in keeping the area a largely intact.landscape. Nevertheless, grazing which is inappropriately intense persists on portions of the mesa top, as well as mountain flanks, thereby threatening further degradation.
References
^ Henry Garber Hanks. 1901. The deep lying auriferous gravels and table mountains of California
^ D.I. Wagner and G.J. Saucedo. 1990. Age and Stratographic Relationships of Miocene Volcanic Rocks along the Eastern Margin of the Sacramento Valley, California. in Ingersoll, R.D. and T.H. Nelson eds., Sacramento Valley Symposium and Guidebook: Pacific Section, S.E.P.M. vol. 65, p. 143-151
^ Samantha Mackey and Albin Bills. 2004. Wildflowers of Table Mountain, Butte County, California. California State Univeristy, Chico, Studies from the Herbarium, number 13 ISBN 0-9761774-0-4
^ C.Michael Hogan. 2008. Blue oak: Quercus douglasii. globalTwitcher.com, ed. N. Stromberg
^ J.D. Jokerst. 1983. The Vascular Plant Flora of Table Mountain, Butte County, California. Madrono 30: (no. 7 supplement) pp 1-18
^ J.D. Sturgeon. 1961. A History of Cherokee Flat, Butte County, California. PhD dissertation. California State University, Chico
^ William Henry Brewer, William Bright and Francis Peloubet Farquhar. 2003. Up and down California in 1860-1864: the journal of William H. Brewer. 583 pages
