64 - René Fowrtau—The Eocene of Egypt. 
the Colne Valley, 3 miles south of St. Albans, is a patch of Chalky 
Boulder-clay resting upon sand and gravel. The gravel comes down 
to a level of about 230 feet, and the Boulder-clay les between the 
levels 250 and 290 feet or thereabouts, whilst the same deposit of 
gravel is from 310 to 335 feet high on the other side of the river to 
the south-east. The presence of a patch of Boulder-clay up the 
Colne River, 12 or 14 miles from the Tilehurst Terrace Gravels, and 
almost as low down as the section line BB, Fig. 2, is remarkable. 
However, the fluvio-glacial gravels near the Boulder-clay patch rise 
as high in places as the section line C C where it passes the confluence 
of the Colne River and the Thames. 
It would appear that the Chalky Boulder-clay ice built up in front 
of it a mass of gravel and sand whose upper surface was considerably 
above the lower level of the ice and boulder-clay. When this takes 
place and the glacier is retreating, large masses of glacier ice are left 
beneath the gravel plain, and these melting out form great pits in 
the alluvial deposits. Such a condition of affairs may now be seen 
in the valley of Hidden Glacier,’ Alaska. 
(To be concluded in our next number.) 
TV.—Tue Divisions or tHe EKocenr or Eoypr AS DETERMINED BY 
THE SuccEssion oF THE Ecutnip Faunas. 
By RENE Fourtavu, Member of the Egyptian Institute, etc. 
VERY remarkable fact in the paleontological study of the 
Eocene strata of Egypt is the succession of echinid faunas, 
which seem definitely localized at well-determined horizons, enabling 
these to be recognized with ease. 
The opening of the Eocene period is marked by the appearance of 
a group consisting of Conoclypeus Delanouei, de Loriol, Plesio- 
spatangus Cotteaut, de Loriol, Linthia cavernosa, de Loriol. C. Delanouet 
characterizes the strata to which the Egyptian geologists have given 
the name of Libyan. L. cavernosa appears almost at the same time 
as C. Delanouei, but disappears earlier ; it is no longer met within © 
the upper beds of the Libyan stage, which are characterized by 
the abundance of Foraminifera of the genus Alveolina, and in which 
a new echinid fauna is recognized. Finally, Plesiospatangus Cotteaut 
occurs only in the central portion of the Libyan stage. 
In addition to these three very abundant species, others of less 
frequent occurrence may be mentioned. Such are Opzsaster thebensis, 
de Loriol, exclusively restricted to the lower part of the Libyan 
stage; the group of Megapneustes (IL. Sickenbergerit, Mayer-Kymar, 
M. Lorioli, Gauthier, If. grandis, Gauthier), and Linthia Delanouet, 
de Loriol, which are only met with in the central portion. 
The upper part of the stage, which has received the special name 
of the ‘‘ Alveolina Series’’, contains, in addition to C. Delanouet, 
Lichinopsis libyca, de Loriol, Eehinolampas Humet, R. Fourtau, 
Sismondia Logotheti, Fraas, Hypsospatangus Lefebvrer, de Loriol. 
C. Delanouei is represented at this horizon by a somewhat peculiar 
1 The Yakutat Bay Region, Alaska, by R. 8S. Tarr, p. 63. 
