46 



Mr. J. Evans on Geological Changes in the 



[Mar. 15, 



The tides round the island of Skye are comparatively simple. The V. 

 to XI. tide from the outside of Mull is gradually retarded to a VI. to XII. 

 stream at the outside of Skye, and then as it rounds the north end of Skye, 

 it is met hy the tidal stream which has rounded the north end of the island 

 of Lewis, and bends round into the inner Sound of Skye, where it becomes 

 a VII. to I. tide ; the course of both stream.s being nearly the same as if 

 there were an embankment from Loch Shell in the island of Lewis to Ru 

 Rea on the coast of Ross-shire. At the same time, another branch of the 

 tide which has rounded the point of xlrdnamurchan flows through the 

 Sound of Skye as a XII. to VI. tide, and being an hour earlier than the 

 tide which has rounded the north end of Skye, it pours with great velocity 

 through Kyle Rea, but only to fill Loch Alsh and Loch Duich ; the retar- 

 dation which it meets with in so doing, making the rise inside of the nar- 

 rows at Kyle Akin so nearly contemporaneous with the rise outside, that 

 there is little stream through that narrow opening ; the flood stream, as I 

 am informed, sometimes flowing in one direction and sometimes in the 

 other, according to the prevailing winds. 



There are many more minute details in these streams which have features 

 of great interest. I have not, however, ventured in the present imperfect 

 state of the data which we possess to enter upon these. I venture, how- 

 ever, to express a hope that before the survey is completed, the data may 

 be obtained for showing, and that the charts may show the direction and 

 rate of the stream at every place and at any time. 



March 15, 1866. 



Lieut. -General SABINE, President, in the Chair. 



The following communication was read : — 



^^On a possible Geological Cause of Changes in the Position of 

 the Axis of the Earth's Crust.'' By John Evans, F.R.S., Sec. 

 G.S. Received February 28, 1866^ 



At a time when the causes which have led to climatal changes in various 

 parts of the globe are the subject of so much discussion, but little apology 

 is needed for calling the attention of this Society to what possibly may 

 have been one of these causes, though it has apparently hitherto escaped 

 observation. 



That great changes of climate have taken place, at all events in the 

 northern hemisphere of the globe, is one of the best established facts of 

 geology, and that corresponding changes have not been noticed to the 

 same extent in the southern hemisphere may possibly be considered as 

 due, rather to a more limited amount of geological observation, than to an 

 absence of the phenomena indicative of such alterations in climatal con- 

 ditions having occurred. 



