Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/453



XXXI. Extract from the Minute Book of the Geological Society.

1810, February 2.

xtract of a letter from Dr. Macdonell, of Belfast, to Mr. Horner, was read, in which an account is given of a stratum of submarine peat and timber in Belfast Lough, situated under the level of ordinary tides, but generally left bare at ebb tides. Nuts are numerous in it, both on the east and west sides of the harbour. On the east side, where calcareous rocks exist, the nuts are filled with calcareous spar, but on the west side, where the rocks are schistose, they are empty. Some of them are perfectly filled, others only partially so, yet the shell appears quite entire, and unchanged by any petrifactive process, although when put into acids some effervescence takes place. Dr. Hutton alledges that no infiltration can happen in circumstances similar to that in which these nuts are placed, for they are immersed in a bed of peat four or five feet thick, and this covered by a deposit of sand, shells, and blue clay, and the whole kept moist and all evaporation prevented by being covered three-fourths of the day by the tide.

An extract of a letter from Dr. MacDonnell, of Belfast, to Mr. Horner, was read, giving an account of some granite veins in slate, in the Mourne mountains.



In some part of these mountains, which are situated at the southern extremity of the county of Down, grey granite forms the summit