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Mineralogy and. Geology. 273 
easily explained ; 3 the material of which this rock is composed, was de- 
posited Tu water, which accounts for its being so coarse, all 
the finer Ronnpiop being carried away: but after the water had subsided, 
there seemed to be a depression, or small. basin, but a few feet in di- 
ameter, inti the water was left to evaporate, depositing a thin layer of 
fine light colored clay, over whieh the Sods walked, The i impressions 
in this layer were very beautiful, but they could not be preserved, as 
th 
shovel. This is precisely like what we often see by the roadside afier 
a heavy rain, where the water is left in small ponds. to settle and evap- 
orate, leaving a fine deposit, on, ines we often find the foot 
of birds. “. 
I have obtained at the south niet of Menugit some hundreds of 
footprints of birds, and some spec fata I have not seen at any other 
eee but have met with no qaa ds. » This loeation ismore than 
half a mile from the river, and nearly, = hundred feet above it; the 
Falls, in consequence of sur a over. which the birds walked 
being destitute of that smooth»poli ied appearance that is necessary to 
receive fine impressions, I have some imens that are 
But some of the “a diag 8 ea for large ones) | have ever 
seen, I obtai of Mount Tom, near South 
ined 
Hadley Falls. If the hetght of sg birds was in tes to the 
length of their feet, when compa 45% some existing birds, they must 
have stood some twenty feet high. But the rocks of this place are too 
coarse to have retained fine impressions of small birds or quadrupeds, 
for when the matter was oe the water was in continual motion, 
so as not to leave smooth surface oe I have one slab con- 
taining -two footprints of a large bi face being very rough and 
peers: but the great weight of echind probably a thousand pou 
more,) ressed the sand so hard rer agers perbely smooth, showing 
+ ert the 
have many. speci peta tenn Wethe hetsfiold, Cote»: ¥ hich show ve 
ben that they are the tracks of ee ; still I consider. them imperfect 
sted. 
downa umber ne inches, the, mud closing up again when the foot 
was withdrawn, leaving no depression on the surface; the tracks are 
seen only by splitting the A irene which the foot 
I have at some localities traced the traeks of a single bird aaa or 
forty feet, when the bird no a nal epaancesst HA s Lknow w from the fact, 
that the first —— would be very slight indeed, being pressed on hard 
sand or clay, and each successive step would.be deeper and deeper, 
until the mud yew the impression-; and when he got into the 
water, though he sett i ; 
eee tae appearance.of the track on the strata —, 
the bird had w - But by removing a thin layer we find the impres- 
sion. This has oftentimes enabled me to ascertain how high the — 
was at the time, or how the layer was out of the water 
the i ineperaniane were made. 
ven 
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