46 
The American Geologist. 
January, 1896 
modified drift supplied by the melting of an ice-sheet which 
had transported the shells from preglacial deposits in the ba¬ 
sin of the Irish sea. 
Furthermore, Mr. Bell directs attention to Geikie’s silence, 
in the new third edition of his “Great Ice Age,” concerning 
the small deposit bearing marine shells found many years ago 
inclosed in the glacial drift at Chapelhall, near Airdrie, on 
which, in the second edition of that work, nineteen years ago, 
a depression of Scotland at least 526 feet below its present 
hight was confidently affirmed. It has since been ascertained, 
by a thorough re-examination of the Chapelhall locality, that 
its fossiliferous deposit was of very small extent, as if a boul¬ 
derlike mass of the old sea bed had been carried there in the 
glacial drift. 
Since this supposed evidence of a considerable submergence 
in Scotland during some stage of the Glacial period has failed, 
a new and apparently more convincing section of modified 
drift, holding marine fossils and underlain and overlain by 
till, is found at Clava, in the valley of the Nairn, a few miles 
/eastward from Inverness. The section shows the following 
deposits, in descending order from the surface, which is 566 
feet above the sea: 
Feet. 
Light brown boulder-clay, with many striated stones. 13 
Fine yellowish brown sand, very compact, inclosing a few 
small stones. ... 20 
Dark blue or gray shelly clay, slightly bedded, with very lit¬ 
tle sand or gravel and almost free from stones, except in 
the lower part. 16 
Coarse gravel and sand, and brown stony clay (partially re- 
assorted lower till). 36 
Total.115 
This lowrnr till lies on the Old Bed sandstone. The shell¬ 
bearing layer, 16 feet thick in this section, thins rapidly to 
only about two feet at a distance of 30 yards to the east, and 
to scarcely more than one foot at 160 yards west. From va¬ 
rious features of these deposits, notably the rather distant de¬ 
rivation of the fine clayey silt inclosing the shells, though the 
formations of boulder-clay both below and above consist 
chiefly of debris of the contiguous sandstone, and on account 
of the absence throughout Scotland of other evidences of any 
submergence during Glacial times excepting about 100 feet 
