Revieios — Newell Arber's Scenery of North Devon. 367 



the apparent sequence is the real succession", and in his map he 

 places the Slates at the top of the Middle Devonian, above the 

 Ilfracombe Beds. The great series of Culm Measures is divided into 

 Lower and Upper Carboniferous. The latter group, as -Mr. Arber 

 demonstrated in 1904, x includes representatives of the Lower and 

 Middle Coal-measures ; while the Lower Carboniferous, in the 

 Boscastle District, consists chiefly of "black shales, with subordinate 

 bands of sandstone and occasional deposits of Radiolarian cherts". 

 The junction on the coast between Lower and Upper Carboniferous 

 north of Boscastle is regarded as a thrust-plane, and no section of the 

 junction is visible on the northern side of the basin near Appledore. 



Much yet remains to be done in working out the detailed succession 

 of the Upper Carboniferous rocks, and this has not been attempted by 

 the author. What is wanted now is a detailed section along the coast, 

 and the author has paved the way for the accomplishment of this great 

 task. His work will be an invaluable guide to all geologists and 

 others desirous of investigating the coast sections. It would be 

 appropriate as a prize in educational establishments. 



Some parts of the coast can only be safely reached by boat ; some 

 cliff-paths are dangerous in windy weather, and a number of them are 

 but little used. The author, however, gives clear directions with 

 regard to the best way to get to each district, noting the most suitable 

 head-quarters in it, together with particulars of 6 inch and other 

 maps ; he likewise recommends three golden rules : " First of all, 

 study the length of beach to be traversed on a large-scale map, and 

 also, if possible, from the cliff-top before the attempt is made. 

 Secondly, make sure of the tides beforehand ; and thirdly, never 

 venture alone." Rock-climbers, as he remarks, will find in the 

 roughest portions of this coast "a new paradise", for "No words 

 can convey the wildness and gTandeur of these cliffs ". 



With these and other preparations the reader is taken from Porlock 

 to Boscastle in six stages, the districts being divided as follows : 

 (1) Lynton, (2) Ilfracombe, (3) Mortehoe, (4) Clovelly, (5) Hartland, 

 and (6) Boscastle. 



The author points out and shows in his excellent plates that there 

 are two distinct types of cliff — (1) that of the Hog's-back, rounded 

 hills sloping steeply towards the sea with but low cliffs, and often 

 wooded to near the sea-level, as at Porlock, Lynton, Heddon's Mouth, 

 and Mortehoe ; and (2) the flat-topped cliffs, with nearly vertical 

 faces, as at Clovelly, Hartland, and Boscastle. These are alike spoken 

 of as " sea escarpments ", but it is usual to confine the term escarpment 

 to inland features. It is true that the Hog's-back features are in the 

 main formed by subaerial denudation, like the inland ranges of Exmoor, 

 and have been undercut when brought under the action of the sea. 

 On the other hand, the flat-topped cliffs "are the product of sea 

 erosion on an elevated, flat, or gently sloping tableland", and have no 

 connexion with subaerial escarpments. 



With regard to the main outlines of the coast the author points out 

 that there are no special reasons connected with exceptional hardness 

 of the rocks to account for the headlands of the Foreland and of 

 1 Phil. Trans., ser. B, vol. 197, p. 291. 



