ISLE OF MAN. GEOLOGY. LIMESTONE. 553 



varies every where ; rarely exceeding two feet, and seldom 

 descending to three or four inches. In consequence of 

 the general flatness of their position, and that of the 

 shore, large portions are in many places completely ex- 

 posed by the recess of the tide; and, being thus also 

 perpetually washed, they admit of being examined in the 

 fullest manner. In many places indeed, access may be 

 had to the edges of the beds, from the surfaces even 

 down to the schist. This is more particularly the case 

 between Derby haven and Langness peninsula ; the low- 

 est points of the limestone being visible in contact with 

 the schist near the Santon river on one side, and with 

 the conglomerate near Langness point on the other ; 

 while the uppermost beds are exposed in many interme- 

 diate points, if these can be determined, as they appear 

 to be, by a particular breccia hereafter to be described, 

 which covers them. The thickness of the collective mass 

 is necessarily greatest at some of these intermediate points, 

 and diminishes in approaching the schist on the one hand 

 and the breccia on the other. That thickness, were it an 

 object of any moment, might be estimated by carefully 

 tracing the exposed edges of the beds. In some attempts 

 at boring which were once instituted in pursuit of coal, 

 forty-five or forty -six fathoms were passed through with- 

 out reaching the fundamental rock. 



Although the general position of the limestone beds 

 is flat, it is rarely quite horizontal. Such a disposition 

 however occurs in two or three places, where, in con- 

 sequence of a slow and gentle undulation of the strata, 

 the tendency of the dip becomes reversed. In these 

 cases a variation of the angle of inclination takes place, 

 amounting to ten degrees or more, and the tendency of 

 the dip necessarily varies : at Santon river it is south, 

 near Port la Marie east-south-east, while in other places 

 it respects other points of the compass. 



In a few places, the inclination of the limestone is much 

 greater than that above mentioned, and these cases occur 



