492 CLARK AND BIBBINS 
who has made a very exhaustive study of the flora from this 
horizon, represent among their number a few archaic types, 
while others approach quite closely to modern types of vege- 
tation. 
THE RARITAN FORMATION. 
Name and areal distribution—The Raritan formation receives 
its name from the Raritan Bay, New Jersey, where the deposits 
of this formation are typically developed. The name was given 
by the senior author of this paper in the annual report of the 
state geologist of New Jersey for 1892 although the term Raritan 
clays had been somewhat loosely used for deposits of this age 
by earlier writers. 
The Raritan formation extends as a constantly narrowing 
belt from northern New Jersey into Maryland and disappears by 
the transgression of the upper Creteaceous formations near the 
borders of the District of Columbia. 
Leading featurcs of the deposits —TVhe deposits of the Raritan 
formation consist of sands and clays, the former largely pre- 
dominating in the upper portion of the formation. The sands 
are frequently very pure and white but at times, especially in 
the lower portion of the formation are more or less colored and 
indurated by hydrous oxide of iron which produces the char- 
acteristic tube-like structure which is known as ‘pipe ore.’ 
The indurated beds are well exhibited at Rocky and Stony 
creeks on the south side of the Patapsco River, and at White 
Rocks in the immediate vicinity. The latter locality afforded the 
name of ‘‘ Albirupean”’ which was applied by Professor Uhler to 
the upper portions of the Potomac group. 
The clays are generally of very light color but at times 
become dark colored in the leaf-bearing zones. Beds of brown, 
black or earthy lignite, containing much pyrites, and occasion- 
ally amber (Cape Sable, Magothy River), have been observed at 
a few points. The clays are generally more or less arenaceous 
and grade over into the sandy deposits which largely character- 
ize this formation. 
