ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxit 
had, many years since, remarked respecting the rocks of this part of 
Ireland, that “‘the character of this andalusite is altered by a more 
or less intimate mixture of mica.” 
Prof. Allman read a paper on erratic blocks of greenstone, found 
scattered over carboniferous slate, im the vicinity of Bandon, county 
Cork. As is well known, Ireland is in many districts covered by gra- 
vels and sands, occasionally mingled with blocks of large rocks, all of 
a comparatively recent geological date. If these be sea-borne, we 
should require the submergence of the land, and generally with its 
present physical features, to a depth of more than 1000 feet beneath 
the present level of its shores. The mode in which thousands of large 
blocks of granite are scattered over the flanks of mountains and over 
districts, facing great valleys, in the counties of Wicklow and Wex- 
ford, are often highly instructive. This ‘drift,’ as it is frequently 
termed, most materially influences the agricultural character of large 
districts in Ireland. 
The communication of Prof. Allman was followed by another from 
Mr. Mallet, in which the latter endeavours to show that the trans- 
port of boulders or erratic blocks may be accounted for by the slow, 
or occasionally rapid movement of semi-fluid masses of mud, sand, 
gravel and blocks, forming the bed of the sea, (and either of suf- 
ficient depth and mass alone, or resting upon a base of rock or other 
materials of very moderate slope,) combed with the sorting and 
transporting power of the tidal streams upon the finer materials of 
the whole mass. Mr. Mallet considers that the mass of a loose sea- 
bottom may be constantly sliding outwards, forming a kind of mud 
glacier, as he terms it, the whole reduced to nearly one-third of its 
weight in air by immersion in water, and moving gradually over slopes 
of three or four degrees, and even less. In this manner he observes we 
may account for the grooving, furrowing and scratching so commonly 
remarked among these accumulations of gravels and blocks, pebbles 
and great fragments of rock being held firmly in the under part of 
the moving mass, and grating against the bottom. These scratches, 
now so commonly found on the surface of rocks in the northern parts 
of the earth, and which may be equally so in the southern, allowing 
for the difference of area there occupied by land, have been long pointed 
out by Dr. Buckland and others in the British islands, and have of 
late been frequently, as is well known, adduced as evidences of the 
former existence of glaciers upon the districts where such scratches 
are found. Mr. Mallet points to this view, and observes that the 
explanation he proposes will apply equally to the facts seen. What- 
ever hypothesis we may adopt m order to approach the truth in this 
matter, we must certainly bear in mind the scratches often so common 
among the pebbles themselves, as well as those upon the rocks be- 
neath the gravel and blocks, as if there had sometimes been a grating 
of the harder parts of the mass upon each other, after its general de- 
posit. This accumulation is often in distinct layers, its parts some- 
times arranged in the manner observable upon beaches, while at the 
same time it is obvious that any rollmg about of the pebbles by 
breaker action would speedily obliterate the scratches both on the 
