Rs AMERICAN FERN JoURNAL 
tal, later tilted in a northwest-southeast direction by 
the great Adirondack mountain-making movement. 
The softer rock around them has been worn away by 
“erosion and their uplifted edges now form a long ridge, 
running north and south which usually slopes gradually 
on the east side and is very abrupt on the west. Over 
one of the sheets is, or was, a thin vein of impure lime- 
stone. From this and the decomposition of the trap 
itself sufficient calcium salts are furnished to the soil 
to support, in favored spots, such lime-requiring species 
as the wall-rue spleenwort and the purple cliff-brake. 
On the floor of the lowland the underlying rocks are 
nearly everywhere buried deep under glacial deposits of 
clay, gravel and sand. The sandy areas, with their 
attendant swamps, furnish congenial habitats for coastal 
plain and other species of acid soils. 
Fern lists have been sent in to the JournaL from 
three localities lying along the trap ridge on a line of 
about 25 miles. The first, from Mr. Irving Holcomb, 
contains, reckoned on the basis used by Mr. Winslow, 
34 species. It covers the entire town of Granby, some 
40 square miles; but most, if not all, of the species, — 
could probably be found within a much smaller area. 
Mr. H. C. Bigelow reports 31 species from a triangle a 
mile at base and extending out two miles on the west 
slope of the ridge in the town of Plainville. But per- 
haps the most remarkable list for this region, because 
of the very small area it covers, is that sent in by Dr. 
E. H. Munger.’ At one point, also on the west slope 
of the ridge, in the town of Avon, there is a hollow in 
which water settles, forming a small swamp. This is_ 
drained by a stream which flows for a short distance 
under ground and finally finds its way to the valley 
through a water-worn cleft in the lower wall of the hol- 
low. Here, on cliff and in swamp and ravine, within ~ 
‘Dr. Munger has also furnished most of the geological information 
given above. 
