Mineral and textural analysis of the Modelo Formation in the eastern part of the Santa Monica Mountains, California: Supplement 1 from "A study of the heavy minerals of the Modelo formation in the eastern portion of the Santa Monica Mountains" (Thesis)

Within recent years there has been a renewed interest among geologists in the field of sedimentary petrography. This interest has been rewarded by the accumulation of much new and interesting data. Careful studies of the textures and mineral compositions of formations have yielded important clues regarding climatic and geographic conditions during ancient times. These studies have made it possible in some cases to correlate unfossiliferous sediments. In this paper the writer is chiefly concerned with the heavy minerals of the Modelo sediments with the view to learning what lateral and vertical variations may occur in the mineral composition of a formation over a small area – a matter which is of great significance if the minerals are to be used as criteria for correlation – and to learn something of the paleogeography during the deposition of the sediments in question. Although heavy minerals have served as the key to many perplexing problems, they have not been universally used with success. Many of the failures however, are directly attributable to unreasonable expectations on the part of investigators