112 PROCEEDINGS OE THE GEOLOGICAL SOCIETY. [Jan. 8, 



east coast of Scotland, consist almost exclusively of more or less 

 isolated patches, often of small extent, on the shores of the Moray 

 Firth. It is possible that the Boulder-clays and other drifts, which 

 attain to so great a thickness in the north-east of Scotland, may 

 conceal other similar patches ; these we can only expect to be revealed 

 to our observation through some favourable combination of circum- 

 stances, in deep natural or artificial sections. 



The masses of Mesozoic strata which are seen at various points 

 round the Moray Firth, are found lying indiscriminately against the 

 different Palaeozoic rocks — namely, the several members of the Old 

 Eed Sandstone, the metamorphic rocks of the Lower Silurian, and 

 the great bosses of granite. The Secondary strata are usually greatly 

 bent and faulted, and often, especially near their junction with the 

 Pakeozoic rocks, very violently contorted. The strata are shown by 

 their palseontological characters to be of various ages, from the Trias 

 to the Upper Oolite, and, as will appear from the present memoir, 

 enable us to reconstruct nearly the whole of the Jurassic series as 

 developed in this northern district. 



None of the beds exhibit evidence of having been beaches- lying 

 upon the old Palaeozoic rocks with which they are now in contact, 

 and made up of their fragments. Common as this phenomenon is, 

 as we shall see hereafter, on the west coast of Scotland, we find 

 nothing resembling it on the east coast, where the conglomerates and 

 grits are never made up of the detritus of the primary rocks lying 

 nearest to them ; but on the contrary the various beds of the series 

 exhibit indications of the most various modes of origin — deep-sea 

 marine, shallow-water marine, littoral, brackish-water, freshwater, 

 and terrestrial. 



It is evident on an examination of these patches of Secondary 

 strata that they form the last remaining vestiges of extensive forma- 

 tions which once covered considerable areas, but have been almost 

 wholly removed by the enormous denudation to which the district in 

 which they are developed has been subjected; it is equally plain 

 that the present position of the patches among the older rocks 

 must be ascribed to accidental causes, which have operated since 

 their original deposition. In almost every instance we can trace 

 the proximate causes of the preservation of the patches, either in \he 

 presence of rocks of especial hardness and capability of resisting de- 

 nuding influences, like the cherty rock of Stotfield, the indurated 

 sandstones of Braamberry Hill, the hard grits of Kintradwell and 

 the breccias of Helmsdale — or in the position and protective in- 

 fluence of surrounding masses of Palaeozoic rocks, as at Eathie and 

 Shandwick. The more remote causes which have contributed to the 

 preservation of the several patches I shall presently demonstrate. 

 That, even as late as the glacial period, the Secondary rocks covered 

 much more extensive areas than at present appears to be proved by 

 the great abundance of their fragments in the Boulder-clay of the 

 east of Scotland. 



The areas covered by the Secondary rocks which have been as yet 

 discovered are, as already intimated, very small ; and as they are 



