78 H. D. Miser — Llano ria, the Paleozoic Land 



summarized as follows the thicknesses of the sediments 

 of these ages in Louisiana and eastern Texas : 



' ' The aggregate thickness of the Cenozoic is commonly between 

 5,000 and 7,000 feet, the Eocene being 2,500 to 3,000, Oligocene 

 and Miocene 2,000 to 2,500, and the Pliocene and Quaternary 

 from 1,000 to 3,000. The upper Cretaceous seems to have the 

 thickness ranging from 1,500 to 2,500 and the lower Cretaceous, 

 where present, from a feather edge to about a thousand feet. 

 Over a large area in coastal Louisiana and Texas the aggregate 

 thickness of the various Cretaceous, Tertiary, and Quaternary 

 formations probably ranges between 8,000 and 12,000 feet and 

 may average about 10,000 feet. 



' ' Apparently most of the formations thicken somewhat toward 

 the coast but the average or aggregate amount of thickening is 

 unknown. To the east there is a notable thinning and rise of cer- 

 tain formations at least ; beds lying at a depth of 2,000 feet near 

 Mobile lie at far greater depths two hundred miles to the west 

 and a similar distance from the coast. ' ' 



Structure of the Gulf Coastal Plain. 



The Cretaceous and later sediments under the Coastal 

 Plain have a general dip of 100 feet or less to the mile 

 toward the Grulf , but those in the Mississippi embayment 

 of the Gulf Plain lie in a downwarped trough of older 

 rocks, where their general dip is toward the Mississippi, 

 which runs through the middle of the embayment. The 

 general dip just indicated ds however broken by many 

 small salt domes in Texas and Louisiana, by some fault p 

 and by several large domes and anticlines, among which 

 are the Sabine uplift and Preston, Jackson, and Hatche- 

 tigbee anticlines. (See figure 1.) 



The Preston anticline,^^ in northeastern Texas and 

 southeastern Oklahoma, extends southeastward as far as 

 Gober, Fannin County, Tex., and is in line or nearly in 

 line with the trend of the Criner Hills uplift,'^^ a subsi- 

 diary uplift in the Paleozoic rocks that lies south of and 

 roughly parallel with the Arbuckle uplift of southern 

 Oklahoma, which involves not only Paleozoic but pre- 

 Cambrian rocks. As the southeast end of the Arbuckle 

 uplift is concealed by rocks of Cretaceous age its extent 



^ Stephenson, L. W., A contribution to the geology of northeastern Texas 

 and southern Oklahoma, U. S. Geol. Survey, Prof. Paper 120, pp. 133, 159- 

 160 and Plate 17, 1919. 



^ Taff, J. A., Preliminary report on the geology of the Arbuckle and 

 Wichita mountains in Indian Territory and Oklahoma, U. S. Geol. Survey, 

 Prof. Paper 31, Plate I and pp. 47-50, 1901. 



