E. A. Smith — Post-Eocene Formations of Alabama. 295 



If the great amount of Post-Lafayette erosion should be 

 counted a difficulty in the way of placing the Lafayette de- 

 posits in the same category with the Pleistocene, we should 

 have the same difficulty in the equally great if not greater, 

 amount of erosion between the Miocene and Lafayette. 



While it must be admitted that the Glacial period stands by 

 itself, sharply distinguished from anything which preceded it, 

 and that Glacial deposits and their derivatives may be clearly 

 distinguished from any other class of deposits, it must also be 

 admitted that the Lafayette beds in their distribution and 

 structure stand out as clearly distinct from anything that pre- 

 ceded them as do the Glacial deposits ; they indicate equally 

 great physical changes, and in many respects, especially in 

 their relations to the underlying formations, more nearly 

 resemble some of the Glacial deposits than they do anything 

 else. Besides, the conditions necessary to glaciation could not 

 have been reached instantly, there must have been physical 

 changes that led up to it and made it possible, and it would 

 seem to me not unreasonable to place these precedent deposits 

 along with those due to the Glaciers themselves in the Quater- 

 nary. 



Pascagoula, and Grand Gulf. — Dr. Hilgard, in his Geology 

 and Agriculture of Mississippi, gave the name Grand Gulf, to 

 a great series of sandstones, mudstones, and clays, which in 

 that state overlies the Yicksburg Eocene. These beds were 

 practically destitute of organic remains except some obscure 

 impressions of plants, and perhaps a shell or two, for which 

 reason it has been impossible to fix the age of the formation 

 more definitely than as post-Eocene Tertiary, and probably as 

 Miocene. In 1889 Mr. L. C. Johnson, while examining the 

 Grand Gulf of Mississippi, discovered near Yernal in Greene 

 County, on or near the Pascagoula River, certain beds with 

 marine or estuarine fossils which he at the time considered a 

 part (the upper member) of the Grand Gulf, but so different 

 as to deserve another name. He accordingly suggested the 

 name Pascagoula. 



In November, 1887, Mr. D. W. Langdon, Jr., under the 

 auspices of the Alabama Geological Survey, made an examina- 

 tion of the banks of the Chattahoochee River from Columbus, 

 Ga., to the Gulf, and discovered nine miles above River 

 Junction (Chattahoochee), overlying the Vicksburg limestone 

 and extending down the river as far as Alum Bluff, a series of 

 marine Miocene beds, consisting of many feet of somewhat 

 siliceous and argillaceous limestones overlaid by highly fossil- 

 iferous sands. The excellent state of preservation of the con- 

 tained shells, renders easy and certain the identification of the 

 geological age of these beds, which is Miocene, the limestone 

 beds and the lowest of the fossil-bearing strata at Alum Bluff 



A.M. Jour. Sci. — Third Series, Vol XLVII, No. 280.— April, 1894. 

 20 



