108 CONTACT-STRTrCTUKE IN BEADGATE-PARK SYENITE. 



under the guidance of Mr. Hill himself ; and a careful examination 

 of thin slices under the microscope had satisfied him that the rocks 

 at both places were true lavas and not altered ashes. 



The President remarked that the transference of rocks formerl}' 

 supposed to be clastic into the massive group was a change that 

 would probably require to be rather extensively made on our maps. 

 There was no doubt that once-fused rocks which had undergone 

 deformation tended to simulate pyroclastic rocks. 



Prof. Bonnet had formerl}'^ been fettered throughout by the wrong 

 identification of the porphyroids of the Ardennes. He felt the diffi- 

 culty of coming to a decision, but believed that the bulk of the rock 

 at Pardon Hill was pyroclastic, for it did not resemble a flow-breccia, 

 and appeared to have assumed its present condition before being 

 crushed. 



