On the Geology/ of Little Ross, Kirkcudbrightshire. 88 



tempted to exclaim, *' And where is the level there from which 

 it can come T' 



If the theory I have suggested be well founded, it must be 

 obvious, that in a great town, or the neighbourhood of it, built 

 on a mass of clay, through which wells are sunlc, there will be 

 a constant, though probably very slow and gradual, subsiding 

 of the surface. Such situations would, therefore, be ill adapt- 

 ed for permanent observatories for astronomical purposes ; as 

 a subsidence of the ground, inappreciable on the earth itself, 

 may produce sensible errors in observations of the heavenly 

 bodies. May not some of the anomalous results obtained at 

 observatories be ascribed to this cause ? 



Bemarks on the Geology of the Island of Little Boss, Kirkcud- 

 brightshire. By Thomas Stevenson, Esq., Civil Engineer. 

 Communicated by the Author.* 



Having been for some time resident on the island of Little 

 Ross, whilst superintending the erection of a sea- light and 

 other works on that coast, I had an opportunity of examining 

 the geology of the island ; and as my observations have led to 

 results which, to myself at least, were unexpected, I have ven- 

 tured to draw up a short account of them. 



Little Ross is situated at the mouth of Kirkcudbright Bay, 

 and is about 1500 feet long by 800 feet broad. Its distance 

 from the nearest point of the mainland is not more than 340 

 yards ; and although there is a depth of about 20 feet at high 

 water, there is nevertheless a narrow ridge by which, in many 

 low spring tides, it is possible for foot passengers to cross over, 

 not, however, dryshod. 



The district in which this island is situated has been gene- 

 rally supposed to exemplify the Cambrian group of the Transi- 

 tion class; and .accordingly the Lifctle-Ross island, at first 

 sight, presents the usual appearances of the grey wacke of that 

 geological epoch. It exhibits also a singular scene of disrup- 

 tion, torsion, and upheavings of the strata, v\ hich attain a height 



* Read before the Wernerian Natural History Society, 8th April 1840. 



