240 Mr Mantel! on the Ripple Marks made hy the Waves, 



it by the Hindu-Coosh, across Candahar and Khorasan ; and 

 lastly as far as the Caspian Sea in Azerbaijan, through an ex- 

 tent of seventy-three degrees of longitude, half that of the 

 Andes. The western extremity, which is volcanic, but covered 

 likewise with snow to Demavend, loses the peculiar character 

 of a chain in the cluster of the mountains of Armenia, con- 

 nected with the Sangalu, the Bingheul, and Cashmer-dag, lofty 

 summits in the pashalic of Erzeroum. The mean direction of 

 the system of the Himalaya is N. ^^° W. 

 ( To he continued.) 



On the Ripple Marks made hy the Waves, observable in the 

 Sandstone Strata of Sussex. By Gideon Mantell, Esq. 

 F.R.S., F.L.S., &c. 



The deep undulations with which the surface of many of the 

 slabs of Horsham-Stone are covered, must have been observed 

 by all who have noticed the pavements in the towns and villages 

 where that stone is employed. In some instances the slabs are 

 so rough as to be made use of for stable-yards and crossways, 

 where an uneven surface is required to prevent the feet of horses 

 from slipping when passing over. Obvious as the cause of this 

 curious appearance seems to be, yet it has been a subject of 

 dispute among men of science, the mind being but too apt 

 to seek for a mysterious agent, to explain effects which have 

 been, and still are being, produced by some simple operation of 

 nature. 



In the case before us, it appears scarcely possible that any 

 one who examines the markings produced by the undulations of 

 water on sand and mud, on the margins of lakes, rivers, and 

 estuaries, or on the sea-shore, can doubt that characters so pre- 

 cisely analogous as those observable in the Horsham-stone have 

 been effected by a similar operation. In the description of the 

 fossils of Tilgate Forest, a short notice is taken of the phenome- 

 non under consideralion : a recent examination of the quarries 

 of Horsham, in company with my friend Mr Lyell, induces me 

 to offer a few additional remarks on this subject. 



