142 Reports and Proceedings — 



They consist of sandstones and shales with thin coaly seams, and 

 their age is placed beyond question by the discovery in them of 

 many well-known plants of the Coal-measures, including species of 

 Lepidodendron, Calamites, Sigillaria, and Stigmaria. 



The Poikilitic strata consist of conglomerates and breccias at the 

 base, graduating upwards into red marls and variegated sandstone, 

 which contain concretionary limestones and occasional bands of 

 gypsum. These strata have not as yet, like their equivalents in the 

 Eastern Highlands (the Reptiliferous Sandstone of Elgin and the 

 Stotfield rock), yielded any vertebrate remains. They were evi- 

 dently deposited under similar conditions with the beds of the same 

 age in England, and are not improbably of lacustrine origin. 



The Jurassic series presents many features of very great interest. 

 The Infralias is better developed than is perhaps the case in any part 

 of the British Islands ; and in the district of Applecross a series of 

 estuarine beds, containing thin coal-seams, is found to be intercalated 

 with the marine strata. 



The Lower Lias, in its southern exposures, presents the most 

 striking agreement with the equivalent strata in England, but when 

 traced northwards exhibits evidence of having been deposited under 

 more littoral conditions ; the lower division (Lias a, Quenstedt) is 

 represented by a great thickness of strata ; while the upper (Lias ^) 

 is absent or rudimentary. The Middle Lias is grandly developed, 

 and consists of a lower argillaceous member and an upper arenaceous 

 one, the united thickness of which is not less than 500 feet. 

 The Upper Lias singularly resembles in the succession of its 

 beds, and its paleeontological characters, the same formation in 

 England. The Inferior Oolite is formed by series of strata varying 

 greatly in character within short distances, and betraying sufficient 

 signs of having been accumulated under shallow- water conditions. 

 Above the Inferior Oolite we find a grand series of estuarine strata, 

 pai'tly arenaceous and pai'tly calcareo-argillaceous ; and this is in 

 turn covered conformably by an unknown thickness of blue clays 

 with marine fossils of Middle Oxfordian age. At the very lowest 

 estimate, the Jurassic series of the Western Highlands could not 

 have had a thickness of less than 3000 feet ! 



The Cretaceous strata of the Western Highlands, though of no 

 great thickness, are of surpassing interest. They consist of two 

 marine series alternating with two others of estuarine origin. At 

 the base we find marine deposits of Upper Greensand age, strikingly 

 similar to those of Antrim, but in places passing into conglomerates 

 along old shore-lines. Above the Upper Greensand beds occur un- 

 fossiliferous sandstones, in which thin coal-seams have been detected, 

 and these are in turn covered by strata of chalk, converted into 

 a siliceous rock, but still retaining in its casts of fossils {Belemnitella, 

 Inoceramus, Spondylus, etc.), and in its beautifully preserved micro- 

 scopic organisms (Foraminifera, Xanthidia, etc.), unmistakable proofs 

 of its age, and the conditions of its deposition. Above this repre- 

 sentative of the highest member of the English Chalk there occur 

 argillaceous strata with coal-seams and plant-remains which are 



