Ixxvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



the shore of the bay, and also discovered the bed whence they had 

 been derived. He also discovered, immediately above it, another 

 fossiliferous bed, the fossils of which, comiprismg A9nmonites cordatus, 

 Belemnites Owenii, and B. Beaumontianus, distinctly proved it to be 

 of the period of the Oxford Clay. This discovery at once removed 

 the freshwater beds from all association with the Wealden strata. 



In the section which the author gives to illustrate the geological 

 structure of this part of Skye, we have represented, in ascending 

 order, — 



1. Lias. 



2. Inferior Oolite. 



3. Middle Oolite. 



4. Imjperfectl^ Columnar Basalt. 



5. Estuary Beds. 



6. Oxford Clay. 



7. Amygdaloidal Trap. 



Thus we have first, in order of time, the deposition of marine beds 

 probably at considerable depths in the sea. Afterwards a mass of 

 igneous matter appears to have been ejected over the surface, which 

 became so elevated as to admit of the subsequent formation of the 

 Estuary beds. Then succeeded depression of the terrestrial surface 

 and the deposition of the Oxford Clay beds, followed in turn by 

 another outpouring of igneous matter. The vesicular character of 

 this latter mass, the author observes, may perhaps indicate its for- 

 mation under a shallower sea. 



This view of the geological sequence of events presupposes the 

 bed of Columnar Basalt not to have been injected between the beds 

 where it is now found. The hypothesis of its having been so in- 

 jected is regarded by the author, for several reasons, as not entitled 

 to much consideration. 



The position of the Estuary beds naturally suggested to Professor 

 Forbes a comparison between them and the similar beds intercalated 

 with the carboniferous portion of the Oolitic strata of Brora in Suther- 

 landshire, and formerly referred to the Wealden formation. Two 

 papers descriptive of these beds were read before the Society in 1843 

 and 1846 by Mr. Alex. Robertson. On comparing the Brora fossils, 

 however, with those from Loch Staffin, Prof. E. Forbes found that all 

 the species, with the exception of one, a little Hydrobia {Paludina 

 comdus, of Robertson), in the one locality differed from those in the 

 other. The author considers that much interesting work still remains 

 to be done in investigating both the igneous phsenomena and the 

 palaeontology of the Hebrides. The latter, especially, presents, in 

 his opinion, one of the finest fields of discovery remaining to be 

 examined in the British Islands. 



According to the views of Prof. E. Forbes, we have seen that the 

 volcanic action by which the lower bed of igneous rock, described by 

 him, was produced, must be referred to the middle of the Oolitic 

 period ; and there is no proof that the bed of amygdaloidal Trap is 

 of later date than the Secondary period. In the island of Mull, how- 



