MUSEUM OF COMPARATIVE ZOOLOGY. i 
Now returning to our excursion in search of the fault west of Lamen- 
tation and going west from the crossing of the Cromwell railroad over 
the Consolidated Road, Fig. 2, we pass two conglomerate ridges, and then 
find a strong bluff of trap (14), deeply quarried at its southern end. 
It is the easternmost and lowest of the bluffs that constitute the Hanging 
Hills. If it be a portion of the main sheet, then the fault may be in 
the little hollow occupied by the quarry branch track (15) of the Con- 
solidated Road, and the trend of the fault would in this case be in the 
line from the south end of the quarry ridge to the north end of Lamen- 
tation Mountain, or N. 55° E., and all the conglomerate ridges and the 
anterior trap ridge of the first day’s section must end as they run north 
to this line. I have seldom found a more pleasing confirmation of a 
theory in a predicted result than was afforded in tracing out this fault. 
Every little ridge, trending about N. 30° E., runs with well maintained 
continuity until it reaches the invisible fracture, and then, without ap- 
parent reason, it promptly ends (16). The farther east the ridge, the 
farther north it extends. The anterior trap ridge obediently follows the 
same rule (8), and so does the little outcrop of shale (5), in the valley 
between the anterior and the main sheets. Lamentation Mountain itself 
falls away for no apparent reason ; its trap sheet seems to be as thick 
here as anywhere, but it cannot cross the invisible line of dislocation. 
Spruce brook, flowing north from locality (11) of the first day’s walk, 
runs on shales for a quarter of a mile after crossing under the road, and 
then cuts down to the back of the trap for a little distance (17); the 
shales soon reappear, but with abnormal dip to the northwest, and 
finally end in a violently dislocated and crushed ledge (18). This is 
undoubtedly close to the fault line. A short quarter of a mile farther 
on, the course of the fault leads to a curious anticlinal, mentioned by 
Percival, which like the last finds explanation by the drag of the fault. 
Departures from the general eastward dip of the monocline are rare, and 
it is interesting to see that they are associated with one another and 
with other phenomena as the common results of a single controlling 
cause. Some isolated knolls of trap near by may possibly be blocks 
caught in the fault, but this is questionable. 
The fault line from the quarry bluff northeastward is thus found to 
maintain a tolerably direct course as far as it has been traced, and it 
follows much the same course as the one discovered in Shuttle Meadow. 
We may therefore expect it to be prolonged to the southwest also. In 
walking in this direction from (15), Fig. 2, there is nothing decisive for 
a mile or so, unless a valley followed by the Cromwell railroad oblique 
