358 Mr, MuRCHisoN on the Strata of the Oolitic Series, Sgc. 



In the annexed tabular arrangement will be found a list of all the additional 

 fossils which the district of Brora has afforded ; and they will be found to con- 

 firm the comparison which has been established between these strata and 

 those of the English oolitic series included between the calcareous grit of the 

 coral I'ag and the base of the inferior oolite. 



Western Islands. 



Loch Staffin. — Skye. 



Freshwater Formation* . 



No indications of secondary strata in a higher part of the series than the 

 upper portions of the great oolite had been noticed in my previous memoir on 

 the coasts of the Hebrides : but^ as masses of shale and other beds are found 

 in elevated positions in the Isle of Skye, between the coast and the central 

 chain of trappean hills of which the Storr forms the leading feature, it might 

 be conjectured without further evidence, that some of these belong to a still 

 higher part of the secondary formations. In confirmation of this opinion may 

 be stated the important fact, that in the low and ruinous cliffs of blue shale 

 associated with zeolitic and amygdaloidal trap on the north-eastern shores of 

 Loch Staffin, were found during my late excursion with Professor Sedgwick 

 flattened masses of shelly limestone containing five species of cyclas, one palu- 

 dina, one neritina? one ostrea, one mytilus, and some undescribed bivalves. It 

 adds materially to the interest of these remains, that two species of the cyclas, 

 the paludina, and the ostrea, prove to be identical with the fossils of one of 

 the upper beds of the weald clay described by Dr. Fitton as occurring in 

 Swanage Bay, Dorsetshire, and in the Isle of Wight. Here, therefore, we 

 have a decided indication of a formation of freshwater — or, at all events, of 

 aestuary — origin, which had never before been traced north of Aylesbury in 

 England; and this would seem to prove, that, although the continuity of such 

 deposits may have been more limited in extent than those of marine origin, 

 still the causes which gave rise to a deposit of the former class in England, 

 may at the same epoch have been producing corresponding effects in the north 

 of Scotland, and in other widely distant localities. 



Oolitic Series in the Hebrides. 



It has been already stated that the highest observed beds of the oolitic 

 series, representing the cornbrash or forest marble, are traversed by several 

 trap dykes at Beal near Portree in Skye. One of these, consisting of por- 



* In the following pages the strata are described in their descending order. Sec PI. XXXV. 



