1873.] BEYCE — JT7EASSIC EOCKS OF SKYE AND EAASAY. 337 



Estuarine beds, including the Ostrea-hebridica bed, which a short 

 distance to the west begins to be overlain by the grey felsite, 

 and is seen nowhere else in the island. This one patch of Middle 

 Oolite, with its isolated capping of trap, has a singular interest. It 

 shows us, even more forcibly than tbe portions remaining in Skye, 

 how great has been the denudation within our area, as well before 

 the outflows of the trap began as in the period subsequent to their 

 entire cessation. The central moor is traversed by many deep, 

 broad, and winding clefts, in which water will not lie, and by 

 others less wide, which render great caution necessary in crossing 

 this part of the island. Here many Middle-Lias fossils were obtained. 

 This Middle Lias is the chief feature of Kaasay ; the development is 

 great, and the fossils abundant, as will be seen by inspecting the lists 

 and Reports. This member of the series occupies the moor and hill- 

 top southwards to the road leading from the mansion-house to Hal- 

 laig ; it is well seen all along the north side of the road, and in the 

 bed of the stream, and abounds here in fossils. These beds descend 

 the glen, and pass down to the south coast, whose beds, overlain and 

 cut through by the felsite, are of the Middle Lias. 



The beds on the west coast occur in a steep sea-cliff, opposite to 

 Portree (see the section across the island, PI. XL, fig. 3) ; they con- 

 sist of superior oolite sandstones and flaggy gritty limestones, sur- 

 mounted by the soft sandstones of the Bath-Oolite series. 



Stjmmaey and Conclusion. 



The facts stated in the preceding detailed sections may now be 

 restated in brief summary, and the general theoretical results set 

 forth. 



The sections viewed in connexion give a series of beds within the 

 area, ascending from the lower part of the Lower Lias to the 

 middle part of the Middle Oolite. The base on which the whole 

 series reposes is the same wherever that base is exposed to view, 

 namely the Torridon or Cambrian sandstone which succeeds the 

 hornblendic gneiss. Has the vast intervening series never existed 

 here? or, having once existed, has it been swept away? In 

 attempting to answer this question we must look to other parts of 

 the same physical area — that placed under like conditions and the 

 theatre of similar events ; we find this in Mull and the north-east 

 of Ireland ; and there we see that between the Cambrian sandstone 

 and the Lias there intervene the Silurian, fragments of the Devonian 

 and Carboniferous beds, fragmentary Permian, and fully developed 

 Triassic beds. In Mull the Liassic series rests on a base of Old Eed, 

 and underneath the overlying trap are beds representing the chalk. 

 In the north-cast of Ireland the lower lias, greensand, and chalk only 

 are found. Now it has been shown by the author of the present 

 paper (Geol. Trans. 2nd ser. vol. v. p. G9), and his friend Mr. Tate 

 (Q,. J. Gr. S. vol. xxiii. p. 298), that this series, reposing along its 

 southern limit on the Plmctic beds and trias, "tails off" north- 

 wards by denudation, bed after bed in ascending order disappearing, 

 until at length only a thin band of chalk separates the overlying trap 



