366 Proceedings of the British Association. 



elder sister science Astronomy, and from the beginning now made, 

 it was impossible to predict bow far investigations like Mr. Hopkins' 

 might eventually be carried. The observations of Mr. Hopkins held 

 true in Cumberland, Derbyshire, and Flintshire ; and some of his 

 cases of complicated dislocation were admirably illustrated in Caer- 

 narvon and Stainmoor. Mr. Sedgwick had himself paid particular 

 attention to the joints of rocks, and had found them connected both 

 with their strike and dip. He had also observed some singular phe- 

 nomena in the Westmoreland slates ; he had seen in them two sorts 

 of joints, and a cleavage which was in a different direction from the 

 jointing. In South Wales the planes of splitting were in one direc- 

 tion with very few exceptions. — Mr. Phillips expressed his high sat- 

 isfaction at the result of Mr. Hopkins' paper, and expressed a hope 

 that the phenomena of geology might, to a certain extent, be ex- 

 plained by such simple laws as regulate the other branches of physi- 

 cal science. With regard to the structure of rocks, which promised 

 to throw so much light upon the subject, he proposed a new term 

 for it, the symmetrical structure. In the examination of rocks un- 

 der the three classes of calcareous, arenaceous, and argillaceous, he 

 had remarked, that the regularity of the structure increased with the 

 antiquity of the rock, which was well exemplified in the older slates 

 and limestones. For this there must be a cause, and this must be 

 a central beat, which has acted most upon the older formations, and 

 least upon the nevs?. Illustrations of the effects of heat upon strata 

 may be obtained from those in contact with dykes, which produce 

 symmetrical structure in rocks or clays through which they pass. 

 Internal heat must then have caused the regular structure so gene- 

 rally observed in rocks. The direction of the fissures pointed out 

 by Mr. Hopkins in Derbyshire, corresponded with the observations 

 of M. De la Beche in Cornwall, and of Mr. Conybeare in Glamor- 

 ganshire. The phenomena of the direction of the joints were well 

 worth investigation, as there was much uncertainty involved. They 

 evidently pointed out the weaker points, or places of least resistance, 

 where the disturbing force would operate with most effect ; and they 

 may have been the result of consolidation, as we find them in con- 

 glomerates, as well as in homogeneous rocks ; still it might be a 

 question, if they were formed before or after dislocation. 

 Section D. — Zoology and Botany. 

 Col. Sykes made a communication to the Section " On the Cul- 

 tivated and Wild Fruits of the Deccan." 



