Davis — Quarries in the Lava Beds at Meriden. 9 



railroad, by which it is hauled away. Some 800,000 tons have 

 been sold in the last five years. In the rough sketch here 

 given, the lower and inner part of the quarries is occupied by 

 what I shall call the lower bed : the upper and outer part by 

 the upper bed. The surface of separation between the two 

 beds may be traced without much difficulty ; it is now very 

 clearly shown at several places, but its distinctness varies with 

 the condition of the quarry. Followed around the various 

 faces of the quarry, this surface may be traced with more or 

 less continuity for six or eight hundred feet ; and if all loose 

 stuff were cleaned away, a length of a thousand feet might 

 probably be measured. I have attempted to show the contact 

 in fig. 3 by a line that breaks the shading at the back of the 

 quarries. 



The deepest part of the lower flow now exposed is in the 

 back of the southern one of the new quarries, where it is seen 

 for about forty feet beneath its surface. Here it is of a bluish 

 gray color, fine-grained and dense, rarely vesicular. Nearer its 

 surface it becomes red or purplish, with an increasing propor- 

 tion of vesicles. The red color does not seem to depend on 

 the weathering of to-day, for it is fully developed deep in the 

 quarries and in massive, unjoin ted rock: it should therefore be 

 ascribed to weathering immediately subsequent to eruption, or 

 to underground alteration. The color is often so strong near 

 the upper surface that this part of the trap might easily be 

 mistaken for baked sandstone. The largest regularly shaped 

 vesicles in the upper part of the flow are nearly an inch in 

 diameter ; in the most vesicular rock the originally empty 

 spaces must have occupied at least a third of the entire volume. 

 Besides the spheroidal vesicles, now filled chiefly with calcite 

 and chlorite, there are occasional irregular cavities, up to six 

 inches in diameter, more or less completely filled with crystal- 

 line minerals, chiefly calcite. Mr. Chapman, foreman of the 

 quarry, assured me that these contain water when first opened 

 in fresh broken rock. With all these secondary minerals, how- 

 ever, this account has little to do. 



The lower bed nowhere exhibits any distinct columnar struc- 

 ture, but has on the other hand a tendency to split into slabs 

 four or five feet thick, along weathered joints parallel to its 

 surface. The scoriaceous surface of the flow is occasionally 

 stripped bare : thus at present there is, in the old quarry near 

 its southern end, an area measuring about sixty by ten or fif- 

 teen feet, where its rolling form is well exposed. It is a typ- 

 ical example of the Hawaiian " pahoehoe." The adjacent 

 swells of the surface measure three to six feet across, and their 

 vertical relief may reach a foot or more. 



