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SEDIMENTATION

DESCRIPTIONS OF SEDIMENTS COLLECTED

The cores obtained with the Emery-Dietz coring device were at the time the longest on record from the open sea (Table 1). It is believed that the unusual lengths of the cores resulted from the relatively soft character of some of the bottom muds, and also from the use of core barrels 20 feet in length and 2½ inches in diameter, equipped with liners of thin flexible celluloid in place of the metal or glass previously used.

Several cores collected in the Guaymas area were over 15 feet long, and one was nearly 17 feet. Approximately 50 cores and about 10 surface snapper samples were taken in this region. The coring was done systematically, along six lines at right angles to the coast, extending from the inner continental shelf to depths of 400 to 1000 fathoms, 20 to 30 miles from shore. In the northern part of the area, the deeper cores were usually finely laminated diatomaceous muds stinking of H2S from top to bottom, and apparently high in organic matter. When dry, the laminations were clearly seen as alternating white and green bands about .2 to 1 mm thick, which became more closely spaced toward the bottom of the core, probably owing to compaction. One core 7 inches long showed about 200 white bands. If these represent annual layers corresponding to seasonal fluctuations in the production of plankton diatoms in the overlying waters, the rate of deposition of these relatively loose muds may be...

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