North Atlantic Pleistocene Problem — Shattuck. 103 
The materials composing it are extremely diverse, and em- 
brace ice-borne boulders, gravel, sand and loam, which change 
their mutual distribution both vertically and horizontallv, after 
the manner of shore deposits. They are frequently much al- 
tered and decayed, and have been derived not only from for- 
mations occurring in the immediate vicinity, but also from those 
found far west in the mountains. In southern Maryland the 
base of the Sunderland terrace lies at about 90 feet, but rises 
gradually toward the northwest, until at Charlotte Hall the sur- 
face of the bench is found at 170 feet. The name of this for- 
mation is derived from the hamlet of Sunderland, situated on 
the divide, in Calvert county. 
After the deposition of this terrace, the country was raised 
and the Sunderland formation suffered greatly from erosion, 
but on the submergence of the region, the rivers which had 
found their way across its surface were transformed into 
estuaries, and the waves of the Wicomico sea beat on the ex- 
posed shores of the Sunderland terrace, and in their turn cut 
cliffs along its margin. After sufficient time had elapsed to 
build up a wide terrace, the country was again elevated and 
subjected to erosion. 
What has just been said regarding the materials which enter 
into the Sunderland formation applies equally well to those 
composing the Wicomico terrace, except that it possesses per- 
haps a larger proportion of sand and loam derived from its sub- 
terrane. In southern Maryland the base lies at about 40 or 50 
feet, and the top, where it borders its ancient sea-clift' at about 
90 feet. Wicomico river in St. Mary's and Charles counties 
suggested the name for this formation. 
The Talbot formation is developed as a bench of variable 
width around the edges of the Wicomico terrace, and frequent- 
ly separated from it in many places by a low scar]:) line. Oc- 
casionally this scarp, which is the ancient sea-clift" of the Talbot 
sea, attains a bight of 30 to 40 feet, notably in Kent county, but 
on the other hand, there are localities where the scar]) seems to 
be entirely lacking, and it is probable that in these places it has 
been destroyed, since its elevation in the manner described 
above. The Talbot formation was built up during a slight sub- 
sidence which followed the elevatit^n and erosion of the Wi- 
comico terrace. Large areas of the Wicomico and Talbot for- 
