178 E. ©. QUEREAU—JAMESVILLE LAKE, NEW YORK. 
than the gorge itself, leading down from the gorge floor to the level of 
Butternut creek, 120 feet below. Itis occupied and has apparently been 
formed by the waters flowing from a large spring near the head of the 
trench. 
Other noteworthy features of this eorge are the evidences of the former 
existence of a lake near its western end and the large amount of delta- 
like accumulations at its eastern extremity. Well developed beds of 
shell marl and of stratified and undisturbed brick clay attest the fossil 
lake. The delta-like accumulations at the eastern end form the north 
wall of the valley for a considerable and the south wall for a short dis- 
tance, and are distinctly terraced on the sides toward the gorge and 
toward the main valley. Thus we have additional evidence of extensive 
water action. 
JAMESVILLE GORGE 
GENERAL DESCRIPTION 
Jamesville gorge (see plate 14, figure 2), like Rock gorge, has a lake, 
nota fossil one, however, but one with water in it, near its west end, and 
terraced delta-like deposits at its east end. Its special features we will 
take up in the following order: 1. The fissures and caves in the vicinity 
of the lake; 2. The peculiar kettle-like depressions found in the neigh- 
borhood ; 3. The channels which traverse in considerable numbers the 
surface of the region; 4. The terraces into which the sides of the channels 
are carved. We shall endeavor in this way to reach an interpretation 
of the topography of the lake and its surroundings, taken in connection 
with what we have already learned in regard to its remoter environment. 
The drift mantle having been scoured from the surface of the country 
rock all about the lake and gorge, the character and topography of the 
latter can be readily noted on all hands. Its surface is seen to be flat 
or hummocky, and in the latter case it is smoothly rounded, not rough 
or jagged. 
FISSURES AND CAVES ABOUT JAMESVILLE LAKE 
An examination of the surface in this locality reveals the fact that it 
is traversed in many places by a remarkable network of fissures. These 
fissures are from a fraction of an inch to 6 or 8 inches in width, and 
extend nearly perpendicularly downward, sometimes to great depths. 
By letting down a stone attached to a line, a depth of 40 feet has been 
measured. It is evident, however, for other reasons that they are much 
deeper than this in places. A study of the rock in situ, in hand speci- 
mens and under the microscope, has led te the belief that these fissures 
develop along the joint structure of the rock. ‘The joints are filled with 
smaller and larger veins of calcite or aragonite, and minute clefts are 
