Art. IX,] Herrick-Johnson, Geology of the Albuquerque Sheet 193 
Middle Cretaceous Upper green sand and 
a few other beds. 
Lower Cretaceous Known collectively as “Lower 
Green sands” consisting of 
green sands and other aren- 
aceous beds. (Dana, 312.) 
In North America the beds are made up of green sand, 
and thick sand beds of other kinds ; also beds of clays, shell 
beds, and in some of the states, especially Texas, limestone. 
The thickness of the beds in New JerseyJs about 500 ft., in Ala- 
bama, 2000 ft., in the Upper Mo. Region, 2000 to 2500 ft., 
east of the Wahsatch, 9000 ft., while in Texas, the general thick- 
ness is about 800 ft. of nearly solid limestone. 
The Cretaceous strata in America were evidently mostly 
deposited by shallow seas or along coasts, while much of the 
strata of Europe at this time were of deep sea origin, as is 
shown by her chalk formations. 
Although comparatively speaking the Cretaceous rocks are 
not found very extensively in North America, yet, in several 
localities, they have important geological features and cover 
several large areas, which have been divided by White into the 
following regions : 
Atlantic Border Region. 
Gulf Border Region. 
Texan Region. 
North Mexican Region 
South Interior Region. 
North Interior Region. 
Pacific Border Region. 
The South Interior Region and the North Interior Region 
are sometimes known as The Great Interior Region. 
The Atlantic Border Region. The Atlantic Border Region 
includes portions of Pennsylvania, New Jersey, New York, 
Delaware, Maryland, Virginia, and South Carolina ; also some 
islands off the coast of New England. 
The formations are composed principally of gravels, clays, 
sands, and marls. Only in a few instances are they of sufficient 
hardness to furnish an exposure of any great value. The aggre- 
