MUSEUM OF COMPARATIVE ZOOLOGY. 79 
Grounds, and although not visibly traversing even the small measure 
of the narrow block, it may be fairly identified as the anterior sheet, by 
reason of its position. Its failure to make a continuous ridge may be 
attributed to weakness resulting from the numerous small faults that 
were seen in the quarry. Farther along in the block, ledges of con- 
glomerate and sandstone (5, 5’) are found in appropriate position ; but 
their strike is seen to turn somewhat west of north, departing thirty 
or forty degrees from the strike prevalent in the Lamentation fault 
block, and thus helping to account for the abnormal trend of the 
southern face of the Hanging Hills. The fault bounding the quarry 
block on the northwest may be found by walking from the conglomerate 
ledges (5) towards a wooded ridge (6), which is soon discovered to con- 
sist of trap, and which must be regarded as the anterior sheet of another 
block by reason of its attitude between the strong bluffs of Cat Hole 
Peaks on the north and the conglomerate ledges (8) on the south. It 
is overlain with fine red shales (7), whose strike is N. 45° W. and dip 
20° N.E.; no contact with the trap has been found here, though it 
might be discovered by a little digging. The several breaks in the front 
of the anterior ridge probably indicate small faults, and may in part be 
associated with corresponding notches in the main sheet. ‘This may be 
called Cat Hole block, taking the name from the deep pass in the main 
sheet on its western side. The view of the block from the round hill of 
conglomerate and sandstone (8) is especially valuable ; no point in the 
district illustrates more clearly the necessity of working out the struc- 
ture of every block by walking parallel to its length, instead of as usual 
at right angles to the strike of the beds. The several members of the 
quarry block can be located : the main sheet in the quarry ridge (1), the 
anterior (4) alongside the Fair Grounds ; the conglomerate and sand- 
stone ledges (5, 5’) below. Cat Hole block is equally distinct ; the 
main sheet in the castellated knobs at the end of the long ridges 
(3 —3); the wooded ridge of the anterior trap with the red shales 
behind it; and the conglomerate ledges below it, where we stand. 
Farther west, Notch Mountain block can be as well interpreted; the 
main sheet in its superb cliffs surmounting a long talus; the anterior 
(9), wooded again, west of us; and the lower sandstones in the rolling 
ground farther south. 
Oblique valleys, undoubtedly located on fault lines, enclose Cat Hole 
block on either side. Taking the anterior sheet as a guide to the dis- 
location on these faults, and regarding its position in Cat Hole block 
(6— 6) as normal, we find it thrown to the northeast in the Quarry 
