MUSEUM OF COMPARATIVE ZOOLOGY. 71 



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 Eoad, 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 



