OKBITAL MOTION AND LATERAL PRESSURE. 53 



then, appear to be the forces which have determined 

 the peculiarities of conformation, which have been 

 so clearly pointed out by the late Rear- Admiral 

 Fitzroy in the following passage, which we extract 

 from the 'Weather Book/ On page 121 of that work 

 Admiral Fitzroy draws attention 



Sf to a very remarkable geologic conformation, common to a 

 great part of our world approachable by sea, though not so 

 much to the far interior of extensive continents : namely, 

 gradual slope up from east towards west, and comparatively 

 precipitous steeps, from summits, westward. Norway, Europe 

 generally, Africa, with its outlying islands, both Americas, 

 the Galapagos, the (elevated) Polynesian islands, the ranges 

 of Australia, China, and Asiatic sea-coasts generally, when 

 viewed extensively in profile from south to north, have the 

 wedge-like outline that is familiar to Englishmen in the Bill 

 of Portland. To the physical philosopher and the geologist 

 we must turn for reasoning on this striking peculiarity one 

 that the writer has often noticed and considered with ex- 

 treme interest. His attention was first drawn to it, by 

 seeing the Galapagos group, from a distance, appearing like 

 several ' Bills of Portland,' all exactly similar in their 

 profile outline when many miles distant. Since that time 

 (1836), many opportunities have occurred for enquiries and 

 careful comparisons, of which the result is a belief, that 

 excepting those greater east and west ranges of mountains 

 embodied within continents, or continental islands (such as 

 Australia and Borneo), the general average direction of 

 ranges or chains of mountains is nearly meridional, and 

 their section approaches that of a wedge (pointing eastward). 

 " This wedge-like shape is common to every little sand- 

 ridge, every shifting shingle bank, formed along shore 

 by wave or tidal action. It is also that of sand-ridges on 



