. Bulletin of the Geological Society of America. Geology. 246 J. F. XEWSOMâCLASTIC DIKES the bottom of the sea cliff, which is about 50 feet high. At its east end the mass cuts the shales to the top of the cliff in a chimney-shaped mass 40 feet across. Throughout this mass of soft sand are irregular wavy bands indicating flow structure. The peculiar wavy banded structure is shown in figure 16, which is from a photograph of the eastern end of the mass, showing its thickest part and also the chimney-like portion. The diatom shale immediately east of the dike dips 15 degrees south, 75 degrees wes
. Bulletin of the Geological Society of America. Geology. 246 J. F. XEWSOMâCLASTIC DIKES the bottom of the sea cliff, which is about 50 feet high. At its east end the mass cuts the shales to the top of the cliff in a chimney-shaped mass 40 feet across. Throughout this mass of soft sand are irregular wavy bands indicating flow structure. The peculiar wavy banded structure is shown in figure 16, which is from a photograph of the eastern end of the mass, showing its thickest part and also the chimney-like portion. The diatom shale immediately east of the dike dips 15 degrees south, 75 degrees west, while that at the west end of the mass dips 10 degrees south, 15 degrees east. The sandstone of this intrusion is practicall}^ free from the odor of bitumen. The line of contact between the adjacent overljdng shale and the sand at the west end of the exposure is irregular. Intrusions of shale occur in the sand mass near the west end of the exposure. At 50 is a dike of soft gray sand vary- ing in thickness from 10 inches to 2 feet. This intrusion is exposed for a hundred feet near the bottom of the sea cliff. At its two ends it cuts the shale beds at angles varjing from 10 "= = to 30 degrees, while at its middle it conforms to the shale beds. This dike is within 100 feet of the large Respini ^ â ^ Creek dike (51). from which it is prob- abl}^ an offshoot. The Respini Creek dike (51, figure 10, and figure 2, plate 28), the largest of the Santa Cruz intrusions, has an exposed width of 600 feet along the sea-clifif immediately southeast of the mouth of Respini creek, and ex- tends one-fourth of a mile inland. It is composed of rather fine grained, yellowish brown and gray sand, free from bitumen. The sandstone varies from soft friable material, from which the cementing material, if ever present, has been leached, to hard compact stone. The surface of the intrusion is much pitted by the action of the waves and by the weather and is broken by many joint planes. At places it
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
