1888. ] 53 [Lewis. 
stone, the greensand Cretaceous rests piled up in high abrupt hills on the 
western shore of Chesapeake bay, crossing the country with an unevenly 
defined breadth of about ten miles; On the Severn river, across the 
southern part of Round Bay, high domes of these clays and loamy sand 
form monumental hills, as for example Mount Misery ; while between 
this river and the head of South river almost equally prominent hills arrest 
the attention of the observer. Crossing the great Patuxent the Cretaceous 
hills again come into view and finally form high and bold prominences 
near the Potomac river. 
On the eastern shore of the Chesapeake, however, the Cretaceous hills 
do not form the bold prominences that have been noticed above, but in- 
stead, rise into gentler eminences, sloping towards the water courses in 
moderate rolls, and finding their greatest development along the low ridge 
which separates the rivers of the Chesapeake from those of the Delaware. 
In this formation we have a repetition of the marine conditions of the 
preceding, but with the added element of the greensand, which now for 
the first time makes its appearance. 
The black loamy beds of this formation are packed with the lignitic 
remains of trees and plants, while the lower lying greensand, and especi- 
ally the upper greensand marl beds, are crowded with the casts and shells 
of many kinds of mollusks. 
From. what is here recorded it will be perceived that in the State of 
Maryland there are three well-defined sedimentary formations resting 
below the Tertiaries, and that the first and last are formed of bold reliefs, 
while the intervening one is comparatively low and flat. 
In reply to the above Professor Carvill Lewis remarked: 
That having spent several months in Baltimore and having had some 
opportunities of studying the geology of that district, in which he had the 
kind assistance of his friend Professor Uhler, he took the liberty of sug- 
gesting certain objections to the conclusions of the foregoing paper and 
to the adoption of the new term ‘‘ Albirupean.”’ 
A series of three formations, belonging to the ‘alluvial column,” is 
here described, of which the lowest (the ‘‘Baltimorean’’) is a series of 
variegated clays and sands, some of which have yielded a fauna and flora 
indicating a Jurassic or Cretaceous age. These have long been known and 
are marked on Tyson’s Geological Map as the ‘‘iron-ore clays’’ and 
appear to be the formation already named the ‘‘Potomac.’’ Upon 
these clays Professor Uhler places his so-called ‘‘ Albirupean,”’ consisting 
sometimes of sands and clays, sometimes of a massive sandstone or quartz- 
ite, containing brachiopods, encrinite stems and annelid burrows ; while 
the uppermost of the ‘three alluvial formations’’ consists of Cretaceous 
greensand. This latter is also well known, having been described by 
Ducatel in 1834. 
As to the ‘Albirupean formation,’’ the speaker held that Professor 
