Diatoms From the Modelo Formation (Upper Miocene) Near Girard, Los Angeles County, California
<p>The abundance of organic shales in the Upper Miocene strata of Southern California and the uncertainty which often has attended the determination of their age, has made a study of the diatoms which they contain desirable. These Upper Miocene shales have been variously mapped as belonging wh...
| Summary: | <p>The abundance of organic shales in the Upper Miocene strata of Southern California and the uncertainty which often has attended the determination of their age, has made a study of the diatoms which they contain desirable. These Upper Miocene shales have been variously mapped as belonging wholly or in part to the Pico, Fernando, Puente, Monterey, and Modelo formations, and it was with the hope of aiding in the clarification of this complex that the present investigation was undertaken. The Upper Miocene is well exposed in many places in Southern California, but seldom are the relations to the underlying formations so well shown as along the North flank of the Santa Monica Mountains in the vicinity of Girard, near the western border of Los Angeles County. Due to numerous road cuts, both for real estate subdivision and for highway purposes, excellent exposures are obtainable across the entire Upper Miocene.</p>
<p>The general locality is indicated on Plate I, which shows Los Angeles County, California, as well as portions of adjacent counties. Plate II, a portion of the Reseda, Calif., and Dry Canyon, Calif., Quadrangles of the United States Geological Survey, shows in more detail the section investigated, as well as the location of the fossil collections.</p>
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