282 Reports and Proceedings. 



had not in any way wished to disparage mineralogy, hut, on the contrary, had at- 

 tempted to classify the different rocks according to their petrological character. He 

 used the term " dolerite " in the same sense as the German mineralogists, hoth as the 

 generic name for the whole series, and also for the coarser variety of basalt. 



3. "On the formation of 'Cirques,' and their bearing upon theo- 

 ries attributing the excavation of Alpine Valleys mainly to the 

 action of Glaciers." By the Eev. T. G. Bonney, M.A., F.G.S. 



The paper described a number of these remarkable recesses, which, 

 though not restricted to the limestone districts of the Alps, are best 

 exhibited in them. The author gave reasons why he could not 

 suppose them to have been formed either as craters of upheaval, or 

 by the action of the sea, or by glacial erosion. "With regard to the 

 last he showed that, even if glaciers had been the principal agents 

 in excavating valleys, there were some cirques which could not have 

 been excavated by them ; and then went on to argue from the fact 

 that glaciers had occupied cirques, and from the relation between 

 them and the valleys, that they could not be attributed to diiferent 

 agents. He also showed that commonly the upper part of a valley, 

 where the erosive action is perhaps least, is very much the steepest, 

 and urged other objections to the great excavatory powers often 

 attributed to glaciers. He then described one or two cirques in 

 detail, and showed that they were worked out by the joint action of 

 many small streams, and of the usual meteoric agents working upon 

 strata whose configuration was favourable to the formation of cliffs. 



Discussion. — Mr. Whitaker suggested an analogy between the cirques and the 

 combes in our own limestone countries. 



Mr. Geikie regarded the cirques as analogous to the combes of Wales and the 

 corries of Scotland. They were not, however, confined to limestone districts, but 

 occurred also in gneiss and granite rocks. He thought that the shape was much in- 

 fluenced by the bedding and jointing of the rocks, as there was an evident connexion 

 between these and the shape of the combes. He could not, however, see his way to 

 account for the vertical cliffs surrounding the cirques. 



The Rev. T. G. Bonney, in reply, observed that though cirques were not confined 

 to limestones, the finest instances occurred in such rocks. When cirques occurred in 

 crystalline rocks, the talus was usually much larger than in limestone. 



n. — April 26, 1871. — Prof. Morris, Vice-President, in the Chair. 

 The following communications were read : — 



1. " On a new species of Coral from the Eed Crag of Waldring- 

 field." By Prof. P. Martin Duncan, M.B., F.E.S., F.G.S. 



Prof. Duncan described, under the name of Solenastrcea Prestwichi, 

 a small compound Coral obtained by Mr. A. Bell from Waldringfield, 

 and stated that it was particularly interesting as belonging to a 

 reef-forming type of corals which has persisted at least from the 

 Eocene period to the present day. The single specimen consisted of 

 several small crowded corallites, having calices from -Jq- to -^ inch 

 in diameter, united by a cellular epithecal coenenchyma. It was 

 much rolled and worn before its deposition in the Ked Crag, and 

 hence the author regarded it as a derivative fossil in that formation, 

 and he stated that it probably belonged to the rich reef-building 

 coral-fauna which succeeded that of the Nummulitic period. 



Discussion. — Mr. Etheridge remarked that the origin of this interesting fossil 



