1847.] GUMMING ON THE GEOLOGY OF THE CALF OF MAN. iFl 



house. Off the western point is the dangerous reef of the Hen and 

 Chickens, the two revolving lights on the Calf, when brought in 

 line, bearing upon them. 



The Stack is a singular pile of rocks near the light-houses, stand- 

 ing out in the sea about fifty feet from the land, as does also the Eye 

 of the Calf, near the Burrough, so called from its being pierced by 

 a natural archway. The Burrough * is pierced in a similar manner, 

 both of them by the continued wearing away of the sea acting at the 

 present, and at a higher relative level, in the direction of the strike 

 of the schists of which they are composed. 



These schists (highly inclined) constitute the main body of the islet 

 of the Calf, their general strike being magnetic S. 70° E. Near the 

 before-mentioned highest point a mass of greenstone appears, and 

 in its neighbourhood the schists are slightly metamorphic. 



The author t discovered a small vein of copper near the Burrough, 

 its strike being S. 60° E. magnetic, and dip at angle of 70°. It 

 has been stated that lead has been found on the islet, but the author 

 has not himself observed any indication of that mineral. 



It is however the object of the present paper more particularly to 

 direct attention to a very singular isolated mass of scratched boulders, 

 gravel and sand, rudely stratified, situated on an elevated point of 



Section (3.) 



the schist near the eastern pile erected for the Trigonometrical Sur- 

 vey, and at a height calculated, by comparison with the known ele- 

 vation of the upper lighthouse:}:, to be 372 feet above the present 

 sea-level. The explanation of the phaenomenon bears upon the so- 

 lution of some difficulties which present themselves in connexion 

 with the distribution of erratic blocks in the Isle of Man, as well as 

 on the depth of the sea m this neighbourhood at the period of the 

 boulder deposit. 



In a paper by the author on the " Tertiary Formations of the Isle 

 of Man," (read before the Society on the 4th of February 1846, and 

 published in the 'Proceedings' in the August number of the Quar- 



* See Section 2. 



t Though the third person is used here and subsequently, this is the original 

 paper and not an abstract, — Ed. 



J The author thinks that the 550 feet given in Dr. Berger's Report of the Isle 

 of Man, in the 2nd volume of the Transactions of the Geological Society, as the 

 height of Spanish Head, is a mispi'int for 350, 



VOL. III. PART I. O 



