380 E. O. Hovey — Trap Ridges of the 



to account for the wide separation of the Mt. Holyoke and 

 Deerfield ranges in Massachusetts, besides others of greater or 

 less extent for other parts of the valley. The cause assigned 

 for the production of these " transverse anticlinals," is that 

 they would be a result of the general movement which caused 

 the usual eastward clip of the sandstone, acting in connection 

 with an uneven foundation of gneisses and schists. Hori- 

 zontal compression produces folds the axes of which are at 

 right angles or nearly so to the direction in which the force 

 acts. Prof. Davis's theory, however, demands the frequent 

 repetition on large and small scales of very peculiar conditions 

 in the crystalline rocks, which as yet have uo proof in obser- 

 vation and do not seem to be probable ; and it seems to 

 necessitate a homogeneity and a tenacity in the sandstone 

 which that rock does not possess. Further evidence against 

 his "faint, dish like folds" is found in the broken character of 

 the subordinate ranges, and in the high southeastward dip of 

 the sandstone near the range E2 and the whole southern part 

 of the Pond Rock region. The strike of the sandstone in the 

 southern part of the Connecticut Triassic region, except in 

 some places near the trap, may be taken as averaging N. 15° 

 E., therefore the tilting force must have acted from S. 75° E. 

 with considerable constancy : such a force could not have 

 produced an anticlinal like that between Pond Rock and 

 Toket Mt. The underlying shale on the northern hook of the 

 former has its strike S. 6d° E., and its dip 23° S., while the 

 sandy shale three quarters of a mile away beneath the latter 

 strikes S. 65°-70° E , and dips 18° N. There are some irregu- 

 larities of strike and dip in the valley between the mountains 

 but the axis of the arch may be taken as being W.N.W.- 

 E.S.E., or nearly parallel to the" direction of the general force 

 tilting the strata of the Connecticut valley Triassic. Since 

 the transverse anticlinal cannot owe its existence to the general 

 tilting force, it may be assigned to another one, viz : dikes 

 having a general W. 1ST. W. course, most of which have not yet 

 been exposed. A ridge which may be the southeastern of 

 such a line of dikes is exposed northeast of the end of Pond 

 Pock on the Branford-Northford road. The exposure is 

 some 500 feet long on this road and the crossroad to North 

 Bran ford village, and is about 100 feet wide. No sandstone is 

 exposed near it to prove or disprove the theory. It may be of 

 interest to note, in passing, that this little ridge is curved 

 with convexity to the west. The range of trap ridges next 

 west of Toket Mt. ends at the entrance to this transverse 

 valley (K, on the map); if extended, it would join the trap 

 ridge just described and satisfy the theory. , The observations 

 necessary to establish this theory for other localities have not 

 been made. 



