418 Crosby and Barton— Carboniferous in Massachusetts. 
a yard or more in diameter, though the great mass of the rock 
is composed of pebbles not exceeding three inches in diameter. 
The higher portions, especially, include considerable sandstone, 
mostly in thin and irregular beds. All the crystalline rocks of 
the region are represented among the pebbles of the conglomer- 
ate, though granite, quartz and quartzite predominate. The 
paste is sometimes ferruginous, giving the red conglomerate de- 
scribed by Hitchcock. 
(2.) The conglomerate gives way upward to red and gray or 
green sandstones which have in the aggregate a ebnsiderable 
thickness, certainly not less than six hundred feet. The differ- 
some localities than in others. Both the red and the green 
sandstones frequently pass into true slates and shales; and in 
the red shales, especially, the ferruginous character is often 
very strongly marked. 
(8.) Above the sandstone series, and forming the summit of 
the formation, come the true coal-measures, which, as well de- 
scribed by Hitchcock, consist very largely of a black, highly 
carbonaceous slate, but also include a large amount of green 
sandstone and shales, with comparatively little red rock. Con- 
glomerate is rare in this series, though not entirely wanting. 
Now, the important point to be made here is, that the first 
and second series described above agree perfectly in both com- 
ition and sequence with the rocks of the Norfolk County 
asin ; that is, the Norfolk County beds are essentially similar 
lithologically and stratigraphically to the lower Carboniferous 
of in basin; but we find in the smaller basin no trace 
of the highly carbonaceous, plant-bearing shales, and anthra- 
cite of the third series. 
able to clinch the proof of their Carboniferous age by the 
discovery, near the middle of the belt, of characteristic Carbon- 
iferous fossils. 
o 
