1873.] JTJDB THE SECONDARY ROCKS OF SCOTLAND. ~ 155 



The geological horizon indicated by this fauna is not less clear 

 than that of the beds below. The age of the thick beds of blue clay 

 at Dunrobin is, without doubt, that of Quenstedt's Lias y (that is, 

 the lower part of the Middle Lias of continental geologists, the 

 higher part of the Lower Lias according to our English classification). 

 These beds were probably deposited in deeper and more tranquil 

 water than were those below them, the conditions indicated being 

 not very dissimilar to those which must have prevailed during the 

 deposition of the equivalent strata in England. The peculiarities of 

 their fauna, therefore, such as the persistence of Ammonites oxynotus, 

 Quenst. (though in a dwarfed condition), and of Belemnites acutus, 

 Mill., both of which species become extinct in the typical localities 

 before the close of the Lias ft period, as well as the rarity of the 

 Ammonites, especially those of the group of the Armati, usually 

 very characteristic of the zone, can only be ascribed to difference of 

 climate or to their geographical position, so remote from the sections 

 which have served as standards of our Liassic classification. 



Although no higher beds in the Middle Lias series are exhibited 

 in Sutherland, owing to the fault referred to, we are fortunately 

 not left altogether in doubt as to the characters assumed by the 

 strata of that age in the east of Scotland. Among the boulders 

 in Elginshire and the adjoining counties, none are more common 

 than masses composed of a fine-grained micaceous sandstone, of a 

 light colour, crowded with fossils which prove them to belong to 

 the horizon immediately above that of the clay just described. 

 Among the localities which have yielded such boulders I may men- 

 tion especially the Loch of Spynie, Lhanbryd, Ashgrove near Elgin, 

 Urquhart, several spots near Banff, &c. 



When I have described the Middle Lias strata of the western 

 coast of Scotland, their similarity to those just described in the 

 micaceous sandstones above and the blue shales below, will be made 

 apparent. It will be seen that during the periods represented by 

 portions of the Middle Lias and the Middle Oolite, more uniform 

 and comparatively deep-water marine conditions prevailed in Scot- 

 land. The full consideration of this and similar questions, however, 

 I reserve for the third part of this memoir. 



At two localities, namely Lhanbryd and Loch Spynie, the frag- 

 ments of the Middle Lias sandstone have been found in such abun- 

 dance as to lead to the impression that the rock is in situ at or near 

 the place. A careful examination of the question, however, shows 

 that the masses of rock are certainly enclosed in the Boulder-clay. 

 The accumulation of portions of the same bed at certain points may 

 be accounted for, as already hinted, by regarding them as brought by 

 an iceberg which had received its freight of detritus at some locality 

 where the parent rock was developed. The species of fossils from 

 these two localities are so numerous, interesting, and well preserved, 

 that I am induced to give lists of them. Those from Loch Spynie 

 are nearly all from the cabinet of that indefatigable collector, Mr. 

 Grant, of Lossiemouth. 



