458 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



The marl and trap are often intimately mixed together like two nonmisci- 

 ble fluids, and the dark-gray or red-brown trap and the pale-gray clay 

 rock produce the effect of Castile soap. Long filaments and sti-ingers and 

 rows of bubbles of the clay go out very generally from the larger masses of 

 the clay rock into the trap in a way explicable only on the assumption that 

 a mass of muddy clay was thi-ust suddenly into the liquid trap. At the 

 north end of the east wall of the cutting is a sheet of the clayey sandstone, 

 wliich is about 12 feet long, a foot wide at the center, and tapering to 

 nothing at the ends. Above and below this the trap is coarsely amygda- 

 loidal, or rather abounding with rounded, beaded, and variously lobed 

 cavities, which are filled with the gray mud.^ Some of the pores were left 

 empty or only partly filled by the mud, and these are filled with white 

 infiltrated calcite, making a striking contrast. In many cases it can be 

 seen that the mud has risen from the stratified mass of the argillaceous rock 

 to form and fill the cavities. That the bubble-like masses of mud have 

 thus risen from this larger mass, and that they are regularly disseminated 

 in the trap and are not simply the filling of supei-ficial steam holes, can be 

 clearly seen, and the trap can be chipped off and layer after layer of the 

 gray drops seen to be isolated in the trap (see PI. Villi, fig. 1, p. 428). 



In one case there can be seen at the height of one's eye, at the south 

 end of the west wall, a series of blocks filled with drops, and the mud mass 

 from which they stream can be seen below, while now the mass containing 

 these mud amygdules is itself shattered and its fragments cemented by 

 more of the same mud (see PI. Villi, fig. 2). In other jjlaces a thin, gray, 

 laminated, sandy shale is confusedly mingled in the trap, its layers being 

 greatly waiped and twisted. Under the microscope the mixtm-e can be 

 seen to be still more intimate, and while there was often a complete 

 emulsion of the two nonmiscible fluids there is only a slight chemical 

 action discernible. Only a microscopic layer of recrystallized carbonates 

 appears." 



In other cases the whole wall has a coarse, conglomeratic look, rounded 



' The later infiltration of calcite has changed this mud into a massive gray rook exactly like the 

 olaystones so common iu the Champlain clays. 



- If anyone visits this most interesting locality, which is situated 4 miles from Holyoke, on the 

 road to Westlield, he will find that the ridge running from the Dibhle house south to the next house is 

 cut by the railroad, showing the trap and the sandstone above. In the swale west of this small ridge is 

 a fault, which can be seen in the brook directly behind the second house. West of this fault the series 

 is repeated, and the broad surface of the trap for a mile north is filled with the foreign material. 



