470 MESOZOIC TIME — REPTILIAN AGE. 



In Alabama the formation consists of — 



1. Earlier Cretaceous? — No. 1?. Dark-blue and mottled shales or clay, 

 with only vegetable remains; 300 feet or more. 



2. Later Cretaceous. — No. 4. (a.) Grayish and yellowish sand, often 

 obliquely laminated : 15 feet, (b.) Gray sand, with fossil shells; 6 feet, (c.) 

 Loose white sand, with shells; 45 feet. No. 5. (a.) Soft white limestone, with 

 shells; 6 feet, (b.) Dark limestone ; 4 feet. (Winchell.) 



In Texas the beds consist mainly of compact limestone, and the larger part 

 are of the Later Cretaceous. Shumard gives the following subdivisions : — 

 Marly clay, 150 feet, overlaid by arenaceous beds, 80 feet (Nos. 1 and 2). 

 («.) Caprotina limestone, containing Orbitolina Texana, etc., 55 feet; (b.) Blue 

 marl, 50 feet : (c.) Washita limestone, 100 to 120 feet (No. 3). ((/.) Austin 

 limestone, 100 to 120 feet (No. 4). (c.) Comanche Peak Group, 300 to 400 feet; 

 (/.) Caprina limestone, 60 feet. 



Other localities of the rocks of the several subdivisions are as follow: — 



No. 1, at different points in New Mexico (Newberry). No. 2, on the north 

 branch of the Saskatchewan, west of Fort a la Corne, lat. 54° N. ; in New 

 Mexico (Meek). No. 3, over the region from Kansas through Arkansas to 

 Texas ; in the Pyramid Mountain. No. 4, in British America, on the Sas- 

 katchewan and Assiniboine; on Vancouver Island; Sucia Islands, in the Gulf 

 of Georgia. No. 5, at Deer Creek, on the North Platte, and not identified 

 south of this. (Meek & Hayden.) 



The Green-sand beds of New Jersey, it is seen, belong to the Later Creta- 

 ceous, while in Europe the earlier and the later Green-sand formations per- 

 tain to the ji'-st half of the Cretaceous period, the part not yet known to be 

 represented in America. These Green-sand beds are, therefore, not confined 

 to a particular epoch, and of late have been found to occur even in the Palaeo- 

 zoic, and to be in progress in existing seas. 



The green grains (called also Glauconite) consist of about 50 per cent, of 

 silica, 20 to 25 protoxyd of iron, 8 to 12 potash and soda (mostly potash), 

 and 7 to 10 water, with also a trace of phosphate of lime. For analyses, 

 see author's Treatise on Mineralogy. 



The glauconite of the Chalk differs from that of the Lower Silurian rocks 

 of Canada (p. 176) in containing no alumina, the latter being a hydrous sili- 

 cate of alumina and protoxyd of iron, with about 8 per cent, of potash. 

 (Hunt.) 



n. Life. 



1. Plants. 

 During the Cretaceous period there was a great change in the 

 vegetation of the American continents. The Cycads of the Triassic 

 and Jurassic were accompanied by the first of the great modern group of 

 Angiosperms, — the class which includes the OaK, Maple, Willow, and 

 the ordinary fruit-trees of temperate regions, — in fact, all plants 

 that have a bark, excepting the Conifers. More than one hundred 

 species have been collected, and half of them were allied to trees 



