548 THE JOURNAL OF GEOLOGY. 
distributed widely over the area of the basin, they are particu- 
larly conspicuous on the low land in the immediate vicinity of 
Mogegy Hollow outlet. 
Bowlders of granite, gneiss, quartzite, and conglomerate are 
found at some points above the probable shore-line on the trap 
ridges. As compared to the bowlders of corresponding material 
below the shore-line, their greater age is shown by their greater 
decomposition. They are regarded as remnants of a pre-morainic 
sheet of drift. 
North of the moraine, iceberg deposits cannot be differen- 
tiated with any degree of certainty from the deposits formed 
directly by glacier ice. 
Clays and silts—Clays and silts, which are believed to be 
lacustrine, are very generally present over the low areas of the 
extra-morainic basin. They underlie all the area of the Great 
Swamp and its immediate surroundings. Within this area they 
do not occur above an altitude of 240 feet. Somewhat similar 
clay has been found in a few places at higher levels, but always 
much below the highest shore-line. The clay of the eastern 
half of this area is covered with fine, sandy loam, which, 
as the moraine is approached, grades into sand and gravel. 
Though more or less buried by stratified drift, clay also occurs 
south of Morristown, southwest of Convent, and southwest 
of Madison. These relationships show that the lacustrine clay 
passes under, and therefore antedates the moraine and its con- 
temporaneous overwash plain. The upper part of the clay may 
represent the bottom-set beds of the extra-moraine stratified 
drift. 
In the Great Swamp area the clay attains great thickness. 
Wells 25 or 35 feet deep do not pass through it. A mile and 
a half south of Green Village it was penetrated to a depth of more 
than 100 feet, although there is no positive evidence that all this 
depositus lacustrine. Dhe Ictsijinere ayanisi std Ga sOln. seme sam 
and a little below the surface is finely laminated, the lamine of 
clay being separated by fine partings of a more sandy nature. 
It is highly calcareous, and frequently contains concretions of 
