Davis — Quarries in the Lava Beds at Meriden. 11 



shallow waters of the estuary into which it flowed, so that its 

 surface was exposed to the air; then before the gradual 

 depression that long prevailed in the region succeeded in sub- 

 merging the lava surface, the second bed may have been 

 poured out on the first. If the top of the first bed did not 

 reach the surface of the estuary waters, it must be supposed 

 that the second flow occurred before a perceptible deposit of 

 sediment had time to form. The probabilities seem in favor 

 of the first supposition : for the close study that has been given 

 to many good contact specimens by Mr. Whittle failed to detect 

 any trace of stratified deposits between the two lavas : but on 

 the other hand, a few grains of quartz were found, not deriv- 

 able from the lava and perhaps best explained as wind-born 

 sand. 



The difficulty of recognizing the double structure of the 

 "trap sheet" on the weathered, drift-covered, and wooded 

 surface of the Quarry ridge prepares the observer not to expect 

 manifest exhibition of double bedded structure in the adjacent 

 ridges of Cat-hole and Notch mountain blocks : but on the 

 back of Notch mountain there are good indications that an 

 upper flow occurs above the greater mass of the sheet.* 



The lava beds no longer lie horizontal as they must have at 

 the time of their extrusion, but dip to the east-southeast at an 

 angle of fifteen or twenty degrees. This is shown by the 

 slope of the vesicular portion of the under bed ; the slope is 

 so manifest that it is well known to the quarry men. The 

 sandstones of the district have a similar dip, thus confirming 

 the idea that the lava beds were essentially level when they 

 were poured out, and that they were afterwards tilted along 

 with the whole mass of the formation. Indeed on this point 

 there can be no doubt with regard to the extrusive sheets ; but 

 whether the intrusive sheets of West and East rocks, near New 

 Haven, were driven between the sandstone beds before or after 

 tilting is not definitely settled. The opinion that they were 

 intruded after the tilting of the stratified beds is generally 

 accepted ; but the general accordance of their dislocations with 

 those of the extrusive sheets in the Meriden district strongly 

 suggests that both the intrusive and the extrusive sheets took 

 their place in the bedded rocks before the tilting and faulting 

 occurred. 



The evidence of faulting, both on a small and a large scale, 

 is remarkably distinct in the Meriden quarries and their imme- 

 diate surroundings. Within the quarries there are several fis- 

 sures, of breadth varying up to five or more feet, filled with 

 fractured rock, now more or less weathered. The greater part 



* Bulletin Museum Comp. Zool., xvii, 1889, 81. 



