. Bulletin of the Geological Society of America. Geology. 652 BROVVX AND O COXXELL THE JURASSIC OF CUBA even older, beds come in, while each formation thickens westward. The stratigraphic relation is clearly that of a marine transgressive overlap toward the east, the late Middle Jurassic sea having encroached upon the western end of the Cuban landmass, which continued to sink through late Jurassic time. The individual divisions of the rock series are thick- est in the Vihales region, and thin out eastward, while the basal con- glomerate occupies a diagonal position and becomes progressively yo
. Bulletin of the Geological Society of America. Geology. 652 BROVVX AND O COXXELL THE JURASSIC OF CUBA even older, beds come in, while each formation thickens westward. The stratigraphic relation is clearly that of a marine transgressive overlap toward the east, the late Middle Jurassic sea having encroached upon the western end of the Cuban landmass, which continued to sink through late Jurassic time. The individual divisions of the rock series are thick- est in the Vihales region, and thin out eastward, while the basal con- glomerate occupies a diagonal position and becomes progressively younger toward the east, as indicated in the restored cross-section (figure 13). Above the Jurassic rocks are about 1,000 feet of irregular, discontinuous limestones with thick beds of dark-colored shale in the upper measures. Figure 12.—Folded Schists North of the Limestone Mountains on the Road to Esperanza and lighter-colored marly shales with sandstone strata near the base. Numerous Rudistes attest the Cretaceous age of these beds, which also contain gastropods, Ostrea and other pelecypods. Submergence must, therefore, have continued through Cretaceous time, although there may have been a retreat of the sea at the end of Jurassic or in Eo-Cretaceous time. At the end of Cretaceous time folding and tilting took place, the verti- cal uplift being greater in the western part of the Province of Pinar del Bio than in the eastern. These diastrophic changes probably con- tinued throughout the Paleocene and were synchronous with similar movements in many other parts of the world at that time. During that. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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