•flOOj GROUPS OF THE CRETACEOUS. 61 



being due S.; in Tennessee, according to Safford's map, the outlines 

 bear N. N. E. In general, therefore, the dip of the cretaceous 

 strata may be briefly defined as diverging from the upheaval of the 

 Catnberland Range, around whose western and southern spurs it 

 farms a crescent shaped belt extending from Tennessee, through 

 Mississippi and Alabama, to the Ocmulgee River ; its average width 

 being, however, much less than that given in Hitchcocks' and LyelFs 

 saps, and not often exceeding fifty miles. 



100. In the cretaceous strata of Mississippi, at least three well 

 defined groups or stages may be distinguished, the middle one of 

 which exhibits two distinct facies, themselves deserving, perhaps, 

 the dignity of separate stages. In preference to designating these 

 stages as the Upper, Middle, and Lower Cretaceous, which might 

 give rise to misapprehensions in reference to their relations to the 

 strata of other regions, I shall apply to them specific names, already 

 recognized and understood to some extent. These groups I shall 

 briefly characterize in general, before passing on to their special 

 description, without, however, for the present, attempting to 

 parallelize them to those of more distant regions ; to do which 

 ^atelligently, the study! have thus far been able to bestow on them, 

 ts hardly adequate. 



I. Lowest. Eutaw Group.* — Bluish black, or reddish, laminated 

 days, often lignitic, alternating with, and usually overlaid by, non- 

 effervescent sands, mostly, (though not always) poor in mica, and of 

 ■<l gray or yellow tint. Contains beds of lignite, very rarely other 

 fossils. Those found (by Tuomey, in Alabama — none in Mississippi) 

 itve silicified, and the sand when indurate, shows a siliceous cement. 



II. Tombigbee Sand Group. — Sharp, strongly micaceous sands, 

 «*f greenish hue, laminated when indurate, and cemented by 

 carbonate of lime. Very unequally developed in different localities, 

 •oLiid apparently subordinate to the Rotten Limestone, into which it 

 shows many lithological transitions, and many of whose fossils it 

 shares. It is remarkable for the large number of species and 

 individuals of Inoceramus which it contains, and also for the 

 occurence in it of the gigantic Ammonites Mississippiensis, Spillm. 



*I adopt this name in view of these beds having been first examined in detail, 

 ?urd recognized as being of cretaceous age, by Tuomey, near Eutaw, Alabama, 

 where they arc characteristically developed. 



