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APPENDIX. 



AN INDEX OUTLINE OF THE GEOLOGY OF ENGLAKD. 



The outline of the geology of England, and the map that accompa- 

 nied it, given in the first and second editions of this work, presented 

 f the author believes) the first distinct general view of the geology of 

 England that had ever been published ; and though several parts of 

 our island have since been more fully examined, the examinations 

 have confirmed the correctness of the leading facts, stated in the edi- 

 tions of 1813 and 1815. 



The author has, since, revisited a considerable part of England and 

 Wales, and collected materials for a more ample detail of their geol- 

 ogy; but the limits of the present volume will not admit of their in- 

 sertion, and it is his intention to publish them in a separate form. 

 This index outline will serve more fully to explain the map and sec- 

 tions, by references to the chapters where the different classes of rock 

 are described. 



In tracing the great outlines of the physical geography of conti- 

 nents and islands, we may generally perceive, that they are deter- 

 mined by the ranges of primary and transition mountains that trav- 

 erse them : these have been compared to the skeletons, on which the 

 other parts of a country are constructed. 



The length of Britain is determined by different groups of moun- 

 tains, which, viewed on a large scale, may be regarded as one moun- 

 tain range, extending north and south (with its ramifications) along 

 the western side of England and Wales, from Cornwall to Cumber- 

 land, and from thence to the northern extremity of Scotland. All the 

 highest mountains in England and Wales are situated in this range, 

 which, in reference to our island, may be called the great Alpine 

 chain. This chain is interrupted by the intervention of the Bristol 

 Channel, and again by the low grounds of Lancashire and Cheshire, 

 which divide it into three groups or ranges ; these, for the sake of dis- 

 tinction, may be denominated the Devonian range, the Cambrian 

 range, and the Northern range. They form the Alpine districts of 

 England (coloured red in the map.) The mountains of the great Al- 

 pine chain from Cornwall to Cumberland, are composed of primary 

 rocks and of other rocks, which belong chiefly to the class of transi- 

 tion rocks, described in Chaps. V. VI. and VII. Those parts in 

 which the primary rocks chiefly occur, are shaded by lines. In some 

 few parts, east of the Alpine district, the primary and transition rocks 

 also make their appearance, uncovered by the secondary strata. A 

 range of primary and transition mountains appears once to have ex- 

 tended from the Devonian range, in a north-east direction, into Der- 

 byshire ;— the transition and basaltic mountains of that county, the 



