100 Professor E. Forbes on (he Oolite in Skye. 



the indications presented by the fossiliferous strata which it 

 overlies and alters. 



Another view may be taken, however, of the origin of the 

 basaltic sheet intervening between the upper and middle 

 oolites in Skye, one which would seriously affect the preced- 

 ing estimate of its date. It may be regarded as intruded 

 trap, insinuated between superior and inferior strata at an 

 epoch long posterior to that of the deposition of the former. 

 A minuter investigation of the geological phenomena of the 

 north and west of Skye than has yet been made will probably 

 determine which view is the right one beyond question. But 

 in the present state of the evidence I incline to regard the 

 basalt as contemporaneous with the oolites, and as of the de- 

 finite date which its position in sequence of beds seems to 

 indicate. The great spread and uniform thickness presented 

 by this sheet of basalt, as far as it has been examined, the 

 unaltered condition of the strata which lie upon it, and the 

 baking of the rocks beneath it and of those which the jets 

 connected with it pass through, are facts which determine 

 me at present to regard it as a bed of the date previously 

 suggested. At the same time, in the Loch Stafiin section 

 there are appearances at some of the points where the trap 

 bursts through the superincumbent strata which I could not 

 clearly make out, and which, from their connection with the 

 faulting of the beds, at first sight seemed to indicate disturb- 

 ances produced by the lower trap. My belief at present is, 

 however, that the disturbances alluded to are results of the 

 jets of amygdaloidal trap distinctly seen bursting through 

 the lower and middle oolites and the basalt, and breaking up 

 and baking the estuary beds and Oxford clay, on which the 

 amygdaloid is overspread in mass. 



The area of the Hebrides appears to have been a scene of 

 igneous eruptions and disturbances of level from a very early 

 geological period down to the age of the newer tertiaries. 

 These beautiful and singular islands present a rich field for 

 geological explanation, much as has been done among them. 

 Their palaeontology, one of the freshest and fullest mines 

 for discovery yet remaining in the British Islands, may be 

 said to be unexamined. The working out of the exact re" 



