374 



NOTES ON GEOLOGICAL RESULTS. 



The geological section spent the time in examining the 

 rock, its intrusion (mica trap) and its junction with the gneiss. 

 Of its schistose structure there can be no doubt, and its being 

 placed, by the members, in the hornblend-schist series is, I 

 think, excusable, for in the field there is nothing, if we except 

 its unusual thickness, to lead to a different opinion. At pre- 

 sent the origin of the rock must rest on the petrographical 

 evidence, but it may well be that the Society may find field 

 evidence to support the microscopic later on. 



I have taken the opportunity while visiting quarries 

 during my official work of taking notice of all the hornblend 

 schist met with. In most cases I have been able to trace the 

 schistose portions to more compact portion of the dykes. 



In one case, at Richmond, I was unable to do this, and 

 the schist and gneiss were so irregularly mixed that it was 

 difficult to say which was the older rock, but ultimately I came 

 to the conclusion that the schist was intrusive and that its 

 intrusion had shattered the gneiss and so permitted its admis- 

 sion into lenticular cracks. 



While on this subject I may say that one of the pieces 

 of stone found in the clay at St. Martin's Road was a piece 

 of a schistose character. In Mr. De La Mare's opinion 

 it much resembled in appearance the Cambrian schist of 

 Cherbourg. 



It happened that this piece, found in what I consider to 

 be glacial clay, was striated, and it became important to 

 determine whether it was the schist and therefore brought by 

 ice from France, or hornblend schist, which occurs in many 

 places on the high land here. 



As I have always considered that a local ice cap explains 

 this deposit of clay (one of several) I decided to send speci- 

 mens to England for examination microscopically. 



I therefore forwarded : — 



No. 1. — A piece of the Cherbourg schist. 

 No. 2. — The striated stone from the clay. 

 No. 3. — Hornblend schist from Les Tielles. 



The third piece was chosen with a view of deciding if it 

 belonged to the Pleinmont outcrop of shale or not, for at Les 

 Tielles the schistose rock can be followed until a compact 

 greenstone dyke, from which it originates, is reached. 



I may say that the hand specimens look very much alike, 

 although there are differences of colour and texture, and that 

 these differences had had the effect of our forming a correct 

 classification. 



I herewith give the replies received. 



