1895.] NATURAL SCIENCES OK PHILADELPHIA. 149 



since been eroded arid carried off, or whether they are covered up by 

 the overlapping of the later beds we have as yet no evidence to offer, 

 but if they occupy the same relative position here as in the west, then 

 the presumption is that they never existed and that they occupy a 

 very minor position in the Tertiary scale and were only laid down 

 in isolated positions, and, while differing materially from the great 

 body of the lignitic, should be considered as the equivalent in time at 

 least, to a portion of the basal deposits of that stage. No lignites 

 occur in them and they appear to be at least partly of marine origin. 



Mr. Harris bus classed the Matthews Landing marls, Black Bluff 

 clays aud Midway clay and Limestone of the Alabama Lignitic 

 under the single title 01 " Midway." In this the Texas Survey has 

 followed Mr. Harris and whether the Texas beds will admit of the 

 threefold division made in Alabama, or, if so, where the lines of 

 separation are to be drawn our present information will not allow a 

 definite settlement of the question. As it appears at present these 

 beds can be correlated only with the last two, Black Bluff and 

 Midway. The clays and limestones with their contained fossils as 

 found on the Brazos and in the neighborhood of Elmo and Wills 

 Point correspond closely to these divisions but whether the gray 

 sands and sandy clays with their boulders of calcareous sandstones 

 can be correlated with the Mathews Landing, the proof is at present 

 deficient. 



These beds, unlike the lignitic, cannot be traced continuously 

 across the intervening States. They are not continuous in Texas 

 and only appear as isolated deposits of generally small extent in 

 Arkansas, and Smith seems to think the " Flatwood " in Mississippi 

 belong to the same age. 



The country occupied by the Basal beds in Texas is generally 

 undulating, and prairie-like conditions prevail throughout the 

 northern portion. Towards the south the prairies are broken by 

 growths of dwarf mesquite which is fast covering the whole area. 



r r 



Resume of History. 



The close of the Cretaceous in the East Texas region found the 

 physiographic conditions of the coast line much the same as we find 

 them along the present shore. The coastal plain comprised a series 

 of clays in places, giving place to sauds in others. Nowhere were 

 any of the harder limestones of the upper cretaceous seen. This 



