442 
THE GEOLOGIST. 
with the fine material, being heavy and difficult of transport, will drop do^vn nearly 
at the points where they lie, and remain scattered along the margin of the lake. 
" If, now, the lake be frozen, the expansive force of the ice pushes up everything 
moveable near the shore, and forms a ridge at the uppermost limit reached by the 
congealed water in expanding. This ridge wiU consist mainly of boulders covered 
by and mixed with sand, gravel, and the exuvia; of the shore. When the ice melts, 
everything but the boulders is soon washed away on the side of the ridge towards 
the lake ; and the boulders are there exposed, forming a rough wall. Subsequent 
congelation crowd the boulders closer together against the bank or ridge, and 
render the wall more perfect. In this manner the lakes of Wisconsin, Iowa, and 
Mmnesota have often become girt with wails havuig a very artificial character, 
properly referable to physical laws operating under peculiar circumstances. 
" Several other lakes exist in our immediate vicinity, around whose shores the 
parallel ridges and lines of boulders mark the ancient action of the same causes. 
The third lake exhibits this agency very finely ; and a very extensive marsh, in- 
cluding about 1,500 acres of bog and peat, ten miles west of this place, shows a very 
splendid specimen of this natural wall-building, several miles in length. This is 
Lake Menona, which forms the south-east boundary of om- city. This marsh, like 
most other marshes, was the basin of an ancient lake, and the distribution of its 
boulders marks its outer limits. It is not uncommon for the ridges and walls to 
be pushed up much higher than the adjacent land outside. There is no difficulty 
in supposing, therefore, that the water in the lake might thus stand at a level 
above the land beyond the bank forming its barrier. 
" I sec nothing in the Iowa case that should constitute it an exception. In 
your minute observation in the West, you must have encountered frequent cases of 
this kind. EnwAEB Daniels." 
To Geo. P. Delaplaine, Esq. 
The Enclosed Frogs. — " I have read with pleasure the interesting account of 
the frog found in the Duudalland colliery, ninety yai'ds below the surface, by Jlr. 
Wardlaw Ramsay, given at page o52 of the Geologist. It unfortunately appears 
that such discoveries are beset with difficulties, on account of miners being 
unprepared for the sudden appearance of living reptiles in the progress of their 
operations, or perhaps not having their interest sufficiently awakened as to induce 
them to notice the particulars of such occurrences. But surely this subject is 
sufficiently interesting and important to induce both the zoologist and the geologist 
to endeavour to ascertain the property by which frogs or toads are enabled to 
-ustain life under circumstances in which they are excluded apparently from air 
and food. The late Dr. Buckland, as you. Sir, have observed at page 253, bestowed 
much attention to this very subject, and actually enclosed several specimens of the 
common toad in limestone ; unfortunately, they all died after a short time. It has 
been observed that probably his experiments would have succeeded better had the 
creatures been taken directly from their natural habitats, instead ©f from the melou- 
pit in which they were kept previously to their incarceration in stone. In the 
" Magazine of Natural History," vol. IK., new series, page 518, is an account of a 
toad being taken alive out of the ground, after being buried three feet below the 
surface in flint-gravel ; having remained there undisturbed, under a small flower-pot, 
three years all but ten days. It lived three days after its removal from its dormi- 
tory. Another living toad was then consigned to the same three-feet-deep exca- 
vation, and, after full three years, was taken out of the ground alive from under 
the same flower-pot; this animal died eight days after. — "Magazine of Natural 
History," vol. X., page 180. Had the natural habits of these animals been better 
attended to after being taken out of the ground, they probably would have 
survived mucli longer. In the instances referred to no food was offered them after 
their long abstinence, neither was any care taken of them, as ought to have been 
done considering the importance of the experiments. — Joun Brown, P.G.S., 
Staiiway." 
l'"isii llEMAiNS IN BiTU3!iN0L's-SiiALE. — "Dear Sip.,— As many of your readers 
may not be aware of the interesting fossils contained in the coal-measures, I beg 
to intimate to such as reside iu those districts that it will p^^pay research to 
