ANNIVERSARY ADDRESS OF THE PRESIDENT. Ixxv 
Mr. Mallet brought under its notice some views as to the circum- 
stances under which the quartz rocks and slates of Wicklow have 
been arranged, with some remarks upon a peculiarity of lamination 
im the finer-grained and micaceous slates. His object was to show 
that the component deposits were all due to the sorting and trans- 
porting power of water in motion, the cleaner-washed sand and pebbles 
having formed the base of the present quartz rocks. He referred to 
the diferent conditions under which deposits were now being effected 
in the upper lake of Glendalough, im the county of Wicklow, as a good 
illustration of the sorting and arrangement of deposits at different 
depths. Regarding the ridges and furrows resulting from the fric- 
tion of water upon loose sands, Mr. Mallet points to their occurrence 
in the lake beneath shallow waters, and while remarking upon the sup- 
posed accumulation of certain Silurian deposits in deep water, directs 
attention to the ripple-marks found so frequently among them, ob- 
serving that these must either be confined to shallow waters, or to 
situations where streams of water moving with sufficient rapidity can 
produce them. 
That the quartz rocks of the counties of Dublm, Wicklow and Wex- 
ford are but clean sands or quartz pebbles agglutinated by silica, which 
while in solution, probably often by the aid of an alkali, not unfre- 
quently dissolved the outer edges of the siliceous sands and pebbles, 
appears very probable, indeed is now well understood, and the quartz 
rocks in the district above-mentioned afford good illustrations of this 
view. Respecting the ‘ripple-marks,’ as they have been commonly 
termed,—a bad name, inasmuch as they may readily be produced at 
any depths where a current of water can move with sufficient velocity, 
—we would direct the attention of observers to a study of those really 
made by the to-and-fro motion of waves in shallow water, or where 
tides drain off extensive flats, and to those really due to a constant 
friction of water in a given direction, in order duly to appreciate their 
differences in form. Such a study readily leads to a knowledge of 
the different arrangements of the grains of sand or silt, according to 
the forces acting upon them; a knowledge very material when the 
ridged and furrowed surfaces of various beds (and we find them 
among our oldest accumulations) are brought under our notice. 
Considering it a duty on the part of the Geological Survey to aid 
the progress of the Geological Society of Ireland, Mr. Du Noyer read 
papers on the sections observed on the Dublin and Drogheda Rail- 
way, and Prof. Edward Forbes made a communication respecting the 
probable geological age and British equivalents of the Silurian rocks 
of the hills commonly known from one in particular,—the Chair of 
Kildare. Having with Prof. Oldham examined, during the last 
autumn, the succession of rocks there seen, and ascertained that they 
constituted a thick series of older accumulations, in which volcanic 
ashes or detrital matter derived from igneous rocks, as well as molten 
masses of the latter, were mingled with common sands and mud, 
forming its lower part, I have little doubt of the true relative po- 
sition of the limestone, in which the organic remains are chiefly found. 
Indeed, the whole group of these hills seems little else than an old 
