﻿20 0. Meyer — Tertiary and Grand Gulf of Mississippi. 



Art. III. — Observations on the Tertiary and Grand Gulf of 

 Mississippi ; by Otto Meyer, Ph.D. 



I have spent some time recently in Mississippi, mainly for 

 the purpose of determining the relative positions of the Marine 

 Tertiary and the Grand Gulf formations in the State. Through 

 part of my journey, that is, from Jackson to Terry and from 

 Pelahatchee to Brandon, I had the company of Mr. T. H. Aid- 

 rich, and I am greatly indebted to him for calling my attention 

 to the places in Mississippi which might yield me information. 



The natural valleys which probably give the best informa- 

 tion about the stratification in Mississippi are those of Pearl 

 River and the Chickasawhay at their lowest water level. At 

 the time of my visit, however, the water was too high for such 

 an exploration, and the only means for determining the contact 

 of the Grand Gulf and Tertiary seemed to be systematic exam- 

 ination of the railroads near the frontier of the two formations. 



1. Along the railroad south of Yicksburg, the Yicksburgian, 

 covered by Loess, can be traced along for about a mile ; then 

 the Loess seems to cover everything. 



2. The railroad from Jackson to Natchez has a narrow 

 gauge, and between Jackson and Raymond shows no deep cuts. 

 In Raymond a clayey sand is to be seen. 



3. On the railroad from Jackson to New Orleans we find 

 Tertiary limestone alternating with softer strata one mile north 

 of By ram station, all containing Orbitoides and Pecten. In 

 Byram occurs marl with Yicksburgian fossils. Five and a half 

 miles south of it, that is, half a mile north of Terry, on the 

 creek at the iron railroad bridge, the first sure outcrop of Grand 

 Gulf is found. 



The following profile of the Grand Gulf strata north of Terry 

 was taken by Mr. Aldrich and myself : 



(c) Light sandy clay 10 feet 



(b) Sandstone, hard above, softer below, containing small 



nodules of green clay or corresponding cavities 7 feet 



(a) Green sandy clays 5 feet to water's edge 



Three and a half miles south of Terry, a deep cut about 

 1,400 feet long, shows a remarkable exposure of Grand Gulf 

 strata. They are laminated sandy clays and clayey sands. 

 The fine lamination of the clays is made very conspicuous 

 wherever water runs over them. Laminae of iron concretions 

 also make the stratification more conspicuous. The northern 

 two-thirds of the cut shows a very strong northern dip, abruptly 

 turning over southward in the remaining third with an equally 

 strong dip. The height of the cut at the anticlinal is twenty- 



