EARLIER TERTIARY (EOCENE AND OLIGOCENE). 723 



Province of Santiago. The most westerly locality at which rocks of this age were observed 

 was in the Province of Pinar del Rio, some 4 miles north of the city of that name, on the road 

 to Vinales. Lithologically the material is either soft Hmestone or calcareous marl. There is a 

 quarry in yellowish upper Oligocene limestone at the town of Consolacion del Sur, from wliich 

 a fair collection of fossils was obtained through the kindness of the alcalde of that town. Lime- 

 stones and marls, with a few beds of calcareous sands, occur over large areas in the vicinity of 

 Havana, extending from the city toward the west, south, and east. 



Limestones and marls of the same age, with conglomerates, occupy extensive areas around 

 Matanzas and east of that city. The gorge of Yumuri River is cut through rocks of this age 

 and exposes an excellent section. At this place the river runs nearly east and west through a 

 narrow canyon 500 to 600 feet wide. From its bottom the vertical distance to the top of the 

 highest level through which it is cut is some 450 feet. The gorge itself is about 200 feet in depth'. 

 The rocks dip at an angle of about 27° SE., the thickness here exposed being estimated at 600 

 to 700 feet. The whole section, except the lowest 100 feet, at the west end of the gorge, is 

 composed of limestone, more or less impure, with a few beds of sandstones and conglomerates 

 near the top of the section. Characteristic upper Oligocene fossUs are abundant. The writer did 

 not collect any upper Oligocene fossils in the Province of Santa Clara but has reason to believe 

 that limestones of this age are extensively developed in its northern and southern portions. 



Upper Oligocene yellowish calcareous marl or limestone are found in the vicinity of Nuevi- 

 tas; also at Baracoa, where they immediately underlie the Pleistocene coastal soborruco. There 

 is a very great development of marls and limestones, containing large numbers of reef corals, 

 in and around the city of Santiago. The terraces in this city, excepting the lowest soborruco, 

 have been cut into upper Oligocene formations. Upper Ohgocene limestones have also an 

 extensive development in the vicinity of ManzaniUo. 



G-H 14, H-I 15. TEXAS, LOUISIANA, AND ARKANSAS. 



The following discussion of the early Tertiary of Texas, Louisiana, and Arkan- 

 sas has been compiled by T. W. Vaughan from the literature, from unpublished 

 manuscript or notes of Alexander Deussen, C. H. Gordon, and A. F. Crider, and 

 from the results of his own researches. 



Space will not permit detailed descriptions or geologic sections, and for further 

 information the reader should consult the publications listed in the bibliography 

 (pp. 840-865) under Nos. 297, 299, 370, 401, 406, 407, 408, 430, 485, 486, 487, 488, 

 633, 832, 833, 838. Additional references are given on page 731, and many of these 

 publications contain still other citations. 



GENERAL SECTION. 



The same division of the Eocene into Midway, Wilcox, Claiborne, and Jackson can be 

 made in the Coastal Plain area west of Mississippi River as east of that stream (see p. 731); 

 for the Oligocene, however, a different classification is necessary, as the Vicksburg is not so far 

 west as Red River, and the Apalachicola group is not known in the western area, the sediments 

 stratigraphically equivalent to the Apalachicola being of estuarine or littoral character, similar 

 to those across southern Mississippi. In the table opposite page 724 the section for Arkansas 

 and Louisiana is modified from the one published by A. C. Veatch^^^^' and that for Texas east 

 of Guadalupe River has been furnished by Alexander Deussen. 



EOCENE. 



Midway group-. — The Midway group is extensively developed from Arkansas southwestward 

 across Texas to the Rio Grande. Usually the group has not been subdivided, and the name is 

 therefore applied in a formational sense. However, future studies may lead to subdivision 

 and the adoption of several proposed names for local manifestations. There is a general uncon- 

 formity by erosion between the Midway and the underlying Cretaceous, but it is usually con- 



