3608 PRE-CAMBRIAN NORTH AMERICAN LITERATURE 
This series is the equivalent of the Stamford gneiss in Hoosac Mountain. 
The Algonkian rocks consist of firm, coarse gneisses which contain minerals 
and possess structures not formed in the later rocks; thick beds of coarse and 
highly crystalline limestones which contain many minerals rarely found in 
later limestones, as chondrodite, wernerite, dark pyroxene and hornblende; 
and coarsely crystallized graphite; considerable beds of pyrrhotite, magne- 
tite, and graphite also. 
Because of the presence of the heavy beds of limestones, which were 
probably derived from shells and corals, we may assume that the whole 
series, except the hornblende-gneiss of East Lee, was of sedimentary origin, 
but we know nothing of the limits of the sea in which they were spread. 
These rocks are overlain by the Cambrian Becket gneiss and Cheshire quartz- 
ite. As shown by the basal conglomerate at the Dalton Club House, these 
rocks rest unconformably upon the Algonkian. 
Emerson* describes the geology of Old Hampshire county in Massachu- 
setts, which includes the present counties of Franklin, Hampshire, and Hamp- 
den. On the western border of the Green Mountain area, as it crosses 
Massachusetts and overlooking the Housatonic Valley, is a series of pre- 
Cambrian outcrops, which are the oldest rocks of the state and the sub- 
stratum on which the others rest. They consist of coarse gneisses, especially 
characterized by blue quartz and allanite, coarse porphyritic structure and 
stretching ; and by great beds of highly crystalline limestone, containing 
chondrodite, coccolite, titanite, phlogopite and wernerite. 
The most important of these limestone beds are the Hoosac, the Hinsdale, 
and the Tyringham areas The limestone beds connected with the two latter 
have caused the two most important passes through the range—the Westfield 
Valley and the East Lee-Farmington Valley. 
On the pre-Cambrian rocks rest the Becket conglomerate gneisses of 
Cambrian age, and above them a great series of sericite schists (the Hoosac 
schists, Rowe schists, Chester amphibolite and Hawley schists), which are 
about contemporaneous with the Stockridge limestone of the Housatonic 
Valley. 
Dale? discusses the structure of the ridge between the Taconic and Green 
Mountain ranges in Vermont, and that of Monument Mountain in Great Bar- 
rington, Mass. He finds all the strata concerned to be Cambrian or post- 
Cambrian. 
“Geology of Old Hampshire County, in Massachusetts, by B. K. EMERSON, 
Abstract in Bull. Geol. Soc. Am., Vol. VII., 1895, pp. 5-7. 
2 On the Structure of the Ridge between the Taconic and Green Mountain Ranges 
in Vermont, by T. NELSON Date, Fourteenth Ann. Rep. U.S. G.S. (for 1892-3), Part 
I1., 1894, pp. 525-549; and, The Structure of Monument Mountain in Great Barrington, 
Mass., /ézd@., p. 551-566. 
