ANNIVERSARY ADDRESS OF THE PRESIDENT. 



227 



The Extension of the Older or Paleozoic Bocks below the 

 Newer or Secondary Formations. 



The position and extension of the Palaeozoic rocks beneath the 

 newer formations of the British Islands is a problem of deep interest, 

 and is now occupying much attention in consequence of the facts 

 brought to light by the numerous trials lately made either for the 

 supply of water or in search of minerals. It may be said that ever 

 since the remarkable trials for water at Harwich and Kentish Town, 

 and also the still more remarkable generalizations (almost predic- 

 tions) of R. Godwin- Austen, Esq., in 1856*, and Prof. Prestwich in 

 1872 f, with reference to the possible extension of the Coal-measures 

 beneath the south-eastern part of England, the minds of pure geolo- 

 gists have been excited by speculative views, and desires to arrive 

 at some knowledge of the extension or distribution of old land or 

 Palaeozoic surfaces, so as to restore to the eastward in England the 

 physical geography of those groups of rocks which now constitute so 

 grand a feature along the western side of England, Wales, and Scot- 

 land, but which are lost or covered up beneath the unconformable 

 newer or Secondary rocks. West of long. 1° 30' the greater part of 

 the exposed rocks are Palaeozoic, ranging from the Cambrian to the 

 Coal-measures, their general strike being about N.E. and S.W. 

 East of this meridian are Secondary and Tertiary rocks of great 

 thickness, which doubtless cover the easterly extension of the Palae- 

 ozoic series towards the European continent. The geographical 

 changes of land and sea must have been numerous from the time 

 of the consolidation of the Cambrian sea-bed to the close of the 

 Carboniferous epoch, the rocks of the latter period being deposited 

 in depressions and valleys of the older, with succession or position 

 due to the removal of the subjacent rocks. With the old and wide 

 extension of these earliest-formed masses we are becoming daily more 

 familiar. Looking at the physical structure of the south-western 

 and north-western parts of the British Islands, and the great mass of 

 the older Palaeozoic rocks of North and South Wales, it is evident 

 that from the Cheviots to Cornwall the oldest rocks in Europe are 

 exposed, their eastern extension being hidden. The Northumber- 

 land and Yorkshire coal-fields down to the latitude of Notting- 

 ham are covered and deeply buried by the Triassic, Jurassic, and 

 Cretaceous rocks. South of Nottingham these old land areas are 

 again exposed ; the Charnwood rocks of unknown age, the associated 

 coal-field of Ashby-de-la-Zouch, with the Warwickshire and South- 

 Staffordshire coal-fields stand out like islands in the midst of the great 

 Triassic plain of mid-England ; they are the last isolated exposures 

 or remnants of Palaeozoic land seen south of the great Penine axis, 

 A line drawn from the Malvern range, due south to the Mendips, 

 and thence to Torquay, will define absolutely the exposed line of 

 demarcation between the Palaeozoic and Mesozoic rocks. The mass 

 of North and South Wales stands out in bold relief westward 



* Quart. Journ. Geol. Soc. vol. xii. pp. 38-46. 

 t Popular Science Eeview, vol, xi. p. 241 (1872). 



