No. 4. — The Faults in the Triassic Formation near Meriden, 

 Connecticut : A week's work in the Harvard Summer School of 

 Geology. By William Morris Davis. 



In previous articles on the Triassic formation of the Connecticut val- 

 ley, I have expressed the opinion that faults occun-ed between the ad- 

 jacent trap ridges. The opinion was based on the repetition of similar 

 sequences of strata, the evidence of which will now be stated in greater 

 fulness, so that it may be easily followed in the field by those who wnsh 

 to examine this interesting region. During much of the work, which 

 was undertaken for the United States Geological Survey, I have had 

 the assistance of Mr. C. L. Whittle, who is now engaged in preparing 

 an account of the results of his microscopic observations on the con- 

 tact phenomena of trap and sandstone. After many visits to the region, 

 a plan of exploration of the Meriden-New Britain district was laid out in 

 1887 for the students of the Harvard Summer School of Geology whom 

 I accompanied as teacher, and as it has borne very well the practical 

 test of two seasons of field study, it is adopted for presentation here. 

 The localities were not discovered by any means in the order here de- 

 scribed ; indeed the district was traversed many times before the sys- 

 tematic repetition of its oblique block structure was clearly perceived ; 

 but when this is once made out, it may be best explained by presenting 

 descriptions of its features as daily excursions in a selected order, in 

 which they may be most readily appreciated by a new-comer. 



Excursion 1. — Cross-Section of Lamentation Mountain. 



Meriden serves as a convenient centre for excursions. Its position in 

 central Connecticut and in the southern portion of the Triassic area of 

 New England is indicated by the black square in Fig. 1. About a mile 

 north of the city, (1) on Fig. 2,^ the Meriden, Waterbury, and Connecticut 

 River Railroad (Waterbury and Cromwell Railroad on the sketch maps) 

 crosses over the Consolidated Road (New York, New Haven, and Hart- 

 ford Railroad), and here one may begin the construction of a section 



1 The sketch maps that illustrate this paper are copied from town maps, pub- 

 lished in county atlases. Tiie roads are approximately correct, but the ledges have 

 been located without instrumental measurement. In some cases, the structural 

 lines as now drawn may have to be changed when accurate maps are prepared. 



VOL. XVI. — NO. 4. 



