24 THE HORNBLENDIC AND OTHER SCHISTS OF THE LIZARD DISTRICT. 



EXPLANATION OF PLATE I. 



Fig. 1. Specimen from the Granulitic Group in Kennack Core (p. 17), 

 showing interbanding of light and dark bands of different mineral 

 composition, and an isolated rather fragmental-looking crystal of 

 felspar. 



Fig. 2. Specimen from the Hornblendic Group, Hot Point (p. 4), showing 

 interbanding of layers with variable proportions of felspar and horn- 

 blende, having the appearance of current-bedding. 



Discussion. 



The President was unable to understand how any one who was 

 acquainted with the sections could have the smallest doubt of the 

 intrusive character of the serpentine of the Lizard. 



The Rev. E. Hill remarked that the faulted condition of the meta- 

 morphic rocks was a natural result of their proximity to the in- 

 trusive boss of serpentine. He thought a rock in Sark, probably 

 also of Archaean age, greatly resembled this hornblendic schist of 

 Cornwall. 



Mr. Htjdleston stated that the hornblende schists have a very 

 different composition from the schists at the S.W. angle of the 

 Lizard Point. Some of the so-called hornblende schists greatly 

 resemble a diorite, especially that at Penolver. 



Dr. Hicks expressed his pleasure at finding these Cornish rocks 

 recognized as pre-Cambrian. He had himself recently observed, 

 in some new areas of Archaean rocks he had discovered in South 

 Pembrokeshire, a hornblende schist which simulates the characters 

 of a diorite. He believed the intrusive serpentines also to be of pre- 

 Cambrian age. He remarked on the interest of Prof. Bonney's 

 discovery of a conglomerate in the slate series containing pebbles of 

 the rocks of the metamorphic series. 



Mr. Drew asked for further information as to the grounds on 

 which so small a thickness was assigned to the metamorphic series. 



Prof. Bonney, in reply to Mr. Hudlestorj, admitted that some 

 of the hornblende schists closely resemble diorites, but that when 

 studied in the field such varieties were found to graduate into 

 ordinary hornblende schists. He could find no evidence (though he 

 had expected it) of any of them being altered augitic lavas. He 

 thought it wiser not to attempt to assign a definite place in the 

 Archaean series to the Cornish metamorphic rocks. He did not 

 believe that the metamorphism of the schists was due to the 

 serpentine. In reply to Mr. Drew he said that he had not stated 

 the series to be so thin as Mr. Drew supposed, still at some points 

 there was clear evidence of the repetition of the beds by faults. 



