390 Proceedings of the British Association. 



of the trunks, were adduced to prove that the trees had grown 

 in the place where they now occur. 



After the adjournment of the Section, some of the members 

 proceeded on a geological expedition to Kiliiney, where they 

 examined an interesting junction of granite and mica slate. 



Friday, lUh August. — 13. Mr Whewell offered some very 

 interesting explanations and remarks on various points in phy- 

 sics connected with geology, and more particularly on the per- 

 manency of the half-tide level, on terrestrial magnetism, on 

 Fourier's views regarding central heat, and on the opinions 

 lately expressed in Poisson's Treatise on Heat. 



14. Mr Hartop described some remarkable faults in the south- 

 ern division of the West Riding of Yorkshire, and offered to 

 continue his investigations. 



15. Mr Murchison and Professor Sedgwick gave a lucid and 

 most interesting account of their views regarding the older rocks 

 of England and Wales, endeavouring to point out their subdi- 

 visions, so as to complete the series from the old red sandstone 

 to the oldest slate rocks of Cumberland. Mr Murchison treated 

 of that part of the subject relating to the deposits which occur 

 between the old red sandstone and the slaty rocks of Wales. 

 This group of rocks has been termed by Mr Murchison the Si- 

 lurian System, and has been studied by him during the last five 

 years in Herefordshire, Shropshire, Radnorshire, Brecknock- 

 shire, Monmouthshire, and Caermarthenshire. The detailed re- 

 sults of these important investigations will soon be given to the 

 public in the work by Mr Murchison, which is now in preparation. 

 Professor Sedgwick explained the conclusions he had deduced 

 from his elaborate and extensive examination of the greywacke, 

 or slate series, of the north of England and Wales. Professor 

 Sedgwick divides the old transition series into three groups, viz. 

 the Lower Cumbrian, consisting chiefly of slates, and contain- 

 ing no organic remains ; the Middle Cumbrian, composed of 

 slates, conglomerates, and porphyries, and containing fossils ; 

 and the Upper Cumbrian, which contains much limestone, is 

 fossiliferous, and approaches the lower beds of Mr Murchison's 

 Silurian System. 



