76 BULLETIN OF THE 



from Higby with little interruption. The broad back of the same sheet 

 faulted down in the district of the Hanging Hills, all heavily wooded, 

 rises on the farther side of the wide valley to the west. Descent from 

 the cliff may be made hy t. little crevice, in which a narrow band of brec- 

 cia is seen ; its trend is northeasterly. A southward view of Lamenta- 

 tion with Chauncy at its farther end, and of the north end of Higby, 

 from a point several miles to the north, is given in Fig. 10. Some dis- 

 tance up Falls Brook from High Falls, the sandstone lying on the back 

 of Higby (19), Fig. 9, contains numerous fragments of vesicular trap; 

 stones showing such inclusions are common in the stream bed. 



Attention should here be called to the apparent double ridge at the 

 north end of Higby Mountain ; as if the main sheet were slightly dis- 

 located by a strike fault, or as if it consisted of two lava beds, separated 

 by a weaker stratum of some kind. The main sheet, which forms the 

 bold west bluff of the mountain, ends south of Highland station (16); 

 but a second ridge, a little lower than the first, comes into sight from 

 behind the mountain, and extends a mile or more farther to the north- 

 east (17, 18). This great extension of the second ridge, although so 

 close to the first, suggests a change in the course of the fault, as already 

 indicated. Another example of the double form of the ridge will be 

 found on the excursion for the morrow. 



Excursion 5.— Faults in the Hanging Hills. 



The Hanging Hills, one of the most picturesque districts in the state, 

 may be visited on the fifth day, beginning at the Quarry Ridge, along 

 the margin of which ran the Great Fault discovered on the third day. 

 Approaching the ridge by the lane east of the Fair Grounds, Fig. 11, it 

 is significant that the ledge of conglomerate there followed strikes di- 

 rectly toward the trap bluff and ends on reaching the fault valley. 

 When the quarry (1) is reached, attention will soon be taken by the 

 variety in the structure of the trap, here so well exposed by quarrying. 

 The greatest part is indeed rather uniformly dense and of medium tex- 

 ture, but in the upper platform along the west side of the opening and 

 on the lower bench at the southwest end, much vesicular trap is found, 

 and its relation to the dense trap brings up an interesting problem. 

 Close examination will discover that the dense and vesicular masses are 

 separated by a rather sharply marked surface of gently undulating form, 

 inclined to the eastward at an angle of about twenty degrees, and hence 

 about parallel to the prevailing dip of the monocline. Below this sur- 



