48 



to the level of the old lake, shore-ice seems to have laid hold of 

 such angular fragments of rock as were already loosened by long- 

 continued exposure to the action of the weather, and then, as the 

 frost gave way a little, the icy fringe became detached from the 

 shore and floated away into deeper water, dropping its burden of 

 stones here and there over the bottom of the old lake amidst the 

 finer material accumulated in the ordinary way. Stones dropping 

 through water in this way arrange themselves in layers, and fail 

 more or less on their sides, or, to speak more precisely, with their 

 larger axes parallel to the planes of deposition. Even in our own 

 comparatively-mild winters the ice that forms near the margin of 

 our lakes occasionally freezes into the shingle, and then, when the 

 frost breaks up, drifts away with its tiny load to drop it elsewhere, 

 as the ice melts. Under more severe climatal conditions this 

 action of floating ice becomes an important factor in the formation 

 of the rocks of the present day. In the large lakes of North 

 America, for instance, the break-up of the winter ice must bring 

 about a mingling of no inconsiderable quantity of coarse shore- 

 material along with the finer sedimentary matter drifted in by the 

 ordinary currents flowing into the lake. Breccias similar to this 

 Brockram occur elsewhere in the Lower New Red, and some of 

 these contain stones that are grooved and striated like what we get 

 from deposits of undoubted glacial origin. So I think we need 

 have no hesitation in accepting the view put forward by Professor 

 Ramsay, that these Lower New Red breccias betoken climatal 

 conditions far more severe than any that we are accustomed to in 

 these parts at the present day. Of course, if it can be shown that 

 beds in the Penrith Sandstone have been formed in a more 

 rigorous climate than that we now experience here, the Penrith 

 Sandstone, which was formed at the same time, must also represent 

 a period, or a succession of periods, of severe cold. 



So far, then, I have endeavoured to show that the rock around 

 us contains within itself a record of much of its past history. The 

 various pieces of evidence that the conclusions are based upon are 

 not always of equal value, but they that will take the trouble to 

 inquire fully into the matter will, I think, in the end arrive at 



