XX11. 



of tilings that made it impossible that there was a glaciation south of the Thames. 

 Since then I think I have been able to find evidence that is conclusive ; and 

 I balicve that now one may go a step further and say that there was a glaciation 

 of Dorset. The stones I brought last time had no very marked striation, but they 

 were principally polished stones. Since then I have been able to discover a 

 number of local stones that are not only polished, but striated, and also two 

 more large masses of chalk in the gravel. The striated and polished stones 

 proved that there was dynamic pressure, that is to Bay, pressure with movement. 

 The presence of masses of chalk shows that there was intense cold at the time, 

 for they must have been frozen as hard as flint, or else they would clearly have 

 been ground into powder by the dynamic pressure. These striated stones are 

 found under and around these masses of chalk. They are embedded in a stiff 

 clay. You pick the stones out and put them into a bag, and you do not know 

 whether they are striated or not until you take them home and wash them ; and 

 they are so embedded in the clay that it requires hours, indeed some days, to 

 wash the clay off. It is exactly as you get in the stones from the boulder clays 

 of Norway. If a glacial period is to be proved for Dorset I think that this 

 society ought to have the doing of it and the credit of it. It will be proper 

 in the course of a few months, when there is a convenient opportunity, to put 

 on paper the fresh lines of argument, and to state what are the conditions 

 the unusual conditions of a glaciation upon the chalk, because the conditions 

 must necessarily be different from those that occur in other places on hard rock. 

 That, Mr. President (showing stones), is an example of a polished surface. This 

 is an example of grooving and striation. This is an example of what often 

 occurs where the pressure has been so extreme as to produce that form of 

 fracture from a large piece. If the stone that is crushed happens to be a pebble 

 it is broken into those curious splinters I will bring some next time that 

 pervade the whole of the gravel, and the explanation of which has never yet 

 been given. And when the pebbles are crushed they are splintered rather than 

 striated, although I can produce some striated ones. In other cases the flint is 

 crushed into this form, and on this form there are also striations. This is a much 

 striated pebble. Here is one that has almost a grooving rather than a striation. 

 There is no limit to them now that I know where to find them. 



The PRESIDENT said that it would certainly be of great account if, through the 

 agency of a member of their club, it could be shown, what no geologist has ever 

 yet shown, that the ice- cap once pervaded any part of England south of the 

 Thames. At a meeting of the Geological Society that very month Mr. Marr 

 described the occurrence of a conglomerate deposit of palaeozoic days, made up of 

 clays and pebbles. The pebbles are striated, and showed glacial marks very 

 much like those now seen. But Sir Archibald Geikie, who took part in the 

 discussion, thought that these striations were not brought about by actual glacial 

 action, but by earth movement, in which the conglomerate pebbles struck against 

 one another and thus became grooved. Professor Watts said it was difficult to 

 conceive how any conglomerate which had passed through earth movement could 



