ANNIVERSARY ADDRESS OF THE PRESIDENT. XXXI 



land in the basin of the Clyde, when the climate was colder than 

 at present, sufficiently rapid to have entombed alive the then testa- 

 ceous inhabitants of the sea (littoral and sub-littoral creatures, Myti- 

 lus edulis among them), covering them with a considerable depth of 

 finely laminated clay. 



The shells in the shelly beds are noticed as in place, "the bi- 

 valves with both valves adherent, still covered with epidermis, and 

 the borers in their vertical position." Under a movement of this 

 kind Mr. Smith supposes the ice upon the shores to have been floated 

 to a higher level, bearing up the fragments of rock encased in or 

 supported by it. 



Though many grooves and scratches observable upon the solid 

 rocks and boulders may have arisen, as has been supposed, from the 

 action of glaciers, coast ice, river ice, and the crushing of ice-floes 

 against the land — all varieties of glacial action which have to be re- 

 garded when we consider the effects which may be produced over gla- 

 cial countries and their shores, — there are other groovings which re- 

 quire to be carefully distinguished. In the contortion and squeezing 

 of strata the movement has been sometimes such, that by the sliding 

 of bed upon bed, friction grooves and scratches have been produced, 

 which may be readily mistaken for the others. Again, we find detritus, 

 the pebbles and boulders of which are scratched as well as the sup- 

 porting rocks, as if the whole mass had had an onward movement 

 with sufficient friction of parts to scratch the pebbles and subjacent 

 rocks. Sheets of ice, resting upon the bottom, such as much of the 

 great icy barrier appears to do near Victoria Land, might indeed 

 press heavily and slowly over such a bottom, and, if it were formed 

 of pebbles or boulders, scratch and groove the latter, as well as the 

 supporting rock, in general directions. At the same time we have 

 to regard the friction of a mass of loose materials moving by any 

 means in some given direction, as has been brought under the notice 

 of geologists by Mr. Mallet. Every block of rock in the course of a 

 river which can be moved along during a flood, without being caught 

 up in mechanical suspension, would grate along a bottom, tending to 

 scratch and groove the latter, and its own lower portion. When the 

 volume and velocity of the water were sufficiently great, and the 

 form of the river course variable, the blocks caught up at one time 

 in mechanical suspension and not at another, would fall to the bottom 

 from time to time, grooving and scratching it. These and other 

 causes of scratching and grooving have to be well taken into account, 

 as also artificial scratches and grooves, sometimes without due inves- 

 tigation attributed to glacial action. 



We have also carefully to look into the bars and mounds regarded as 

 ancient moraines, since some of these, upon close investigation, have 

 been found to show that their component parts have been arranged by 

 moving water ; the mode in which the blocks, pebbles and sand are 

 distributed proving this. We have frequently also to guard our- 

 selves from supposing that the larger blocks of such deposits as the 

 so-called boulder clay and till of various districts in our own country, 

 have been always accumulated in greater numbers on the top, or in 



