354 Prof. Silliman on Natural Ice-Hmises in Connecticut. 
nearly twenty miles from the sea, and at the elevation of pro- 
bably not more than two hundred feet above its level. 
The country is a part of the secondary trap region of Con- 
necticut, and is marked by numerous distinct ridges of green- 
stone, which present lofty mural precipices, and, from their 
number, contiguity, and parallelism, they often form narrow 
precipitous defiles, filled more or less with fragments of rocks, 
of various sizes, from that of a hand stone to that of a cottage. 
These fragments are the detritus or debris of these mountains, 
and every one in the least acquainted with such countries, knows 
how much they always abound with similar ruins. 
In such a defile, the natural Ice-House in question is situated. 
On the south-western side there is a trap ridge of naked per- 
pendicular rock, which, with the sloping ruins at the base, ap- 
pears to be four hundred feet high ; the parallel ridge which 
forms the other side of the defile is probably not above forty feet 
high, but it rises abruptly on the eastern side, and is covered on 
the other by wood, which occupies the narrow valley also. This 
valley is moreover choked, in an astonishing degree, with the 
ruins of the contiguous mountain-ridge, and exhibits many frag- 
ments of rock which would fill a large room. As the defile is 
very narrow, these fragments have in their fall been arrested 
here, by the low parallel ridge, and are piled on one another in 
vast confusion, forming a series of cavities which are situated 
among and under these rocks. Many of them have reposed 
there for ages, as appears from the fact that small trees, (the 
largest that the scanty soil, accumulated by revolving centuries, 
can support), are now growing on some of these fragments of rock. 
Leaves also, and other vegetable remains, have accumulated 
among the rocks and trees, and choked the mouths of many of 
the cavities among the ruins. This defile, thus narrow, and 
thus occupied by forest, and by rocky ruins, runs nearly north 
and south, and is completely impervious to the sun’s rays, ex- 
cept when he is near the meridian. Then, indeed, for an hour, 
he looks into this secluded valley ; but the trees, and the rocks, 
and the thick beds of leaves, scarcely permit his beams to make 
the slightest impression. 
It is in the cavities, beneath the masses of rocks already de- 
scribed, that the ice is formed. The ground descends a little to 
