Isabel Creek Melange Terrain
Map SatelliteTypical of a melange terrain, the topography here is hummocky, with many small knolls outcropping above the alluvial valley floor. These knolls are blocks of the more resistant blue schists.
A melange is composed of a chaotic mixture of different-sized angular blocks in a highly sheared, shaly matrix. These blocks include graywacke, shales, cherts, greenstones, etc., and range in size from a few centimeters to several hundred meters in diameter. This melange unit is included within the rocks of the Mesozoic formation.
The deformation of the rock units here appears to have been caused by gravity sliding and is hypothesized to have taken place when the Pacific plate was thrust down under the American plate along a trench zone.
Vegetation in the area has been altered, but foothill woodland and chaparral are present. Two rare plants, Coreopsis hamiltonii and Phacelia phacelioides, occur here.
Integrity: Grazing has altered the vegetation of the area.
Use: Private
October 1976
Inventory of California Natural Areas
Revision © 2009 Steven Louis Hartman