lod 
GEOLOGY AND MINERALOGY. 473 
lying rocks. Between the deposition of the two, an enormous interval of time 
must have oceurred—many intervening formations being absent. It is now 
universally conceded, that, after the deposition of our Palaeozoic rocks, this part 
of Canada was elevated above the sea in which these rocks were deposited, and that 
it remained dry land for many ages, whilst the sueceeding members of the Palaeo- 
zoie series, with the Secondary and Tertiary rocks (properly so called) were 
under process of deposition in the seas, lakes and estuaries, of other localities, 
Then, a movement of depression ensued, and our Province was again covered or 
partly covered by the waters of the ocean. It is also inferred from perfectly 
trustworthy data, that this period was one of comparative cold. Vast glaciers 
were formed in northern regions, from whence numerous icebergs, laden with earth 
and stones, drifted southwards; and gradually melting, or becoming stranded on 
shoals and islands, deposited their rocky freights over the sea bottom. By the 
agency of these floating icebergs also, the limestone ridges were broken down, and 
the calcareous sediments, thus formed, were mixed with the more northern 
deposits. Proois of this are seen in the polished and striated surfaces of our lime- 
stone strata in many localities; in almost all places, indeed, in which a recent 
removal of the Drift has been effected. The polished rock, when first exposed, is 
sometimes as smoeth as a mirror ; and the fine lines which cross it, and which are 
supposed to have been produced by stones and gravel frozen into the under side 
of the icebergs, have almost always a general north and south direction. The 
same effects of ice-action are seen also on most of the exposed gneissoid rocks in 
the northern part of the county. Finally, the ground must have been again 
slowly elevated above the sea; and many of our valleys and other surface 
inequalities were then produced, by the action of waves and currents on the yield- 
ing materials of the Drift and underlying strata. These latter, however, in various 
localities, had been extensively denuded prior to the deposition of the Drift. 
4. Recent Deposits:—These are of very slight extent, and of local occurrence, 
only. They are due te causes which are now in action, or which have prevailed 
during comparatively recent periods. So far as regards the County of Hastings, they 
comprise a few beds of “shell marl,” arising from deposits in swamps and partially 
dried up ponds and lakes. These consist of white and more or less earthy 
ealeareous matter, filied with minute shells of cyclas, planorbis, and other fresh- 
water genera of molluscs. A deposit of this kind occurs on the high ground 
above the west bank of the Moira at.Bellevilles also in the vicinity of Trenton ; 
and at other places. Another recent formation consists of “calcareous tufa” 
deposited on twigs, moss, stones, ef¢., in many streams and springs; but frequently 
both shell marl and calcareous tufa, (properly so called) oceur intermixed, and 
form but one deposit, 
MEGALOMUS CANADENSIS. 
Major Greet of Guelph, C. W., has recently shewn us some comparatively large 
specimens of Megalomus Canadensis obtained in the immediate vicinity of that 
town, a locality, we believe, in which this fossil has not hitherto been announced, 
The rock in which it occurs, is a somewhat porous and sub-crystalline limestone, 
an extension, of course, of the Galt beds. 
Vou. V. 2k 
