J. W. JUDD ON THE SECONDARY ROCKS OF SCOTLAND. 715 



shales passing into hard sandstones and occasionally anto impure 

 subcrystalline limestones. In these beds there can be made out in 

 places traces of Belemnites with Ammonites (too imperfect for spe- 

 cific identifiation), numerous Pectens of large size, and Gryphc&a 

 obliqua^Goldi. These certainly represent some part of the Middle-Lias 

 series. Traced a little further to the west, the fossils altogether 

 disappear, and the rocks pass into the so-called Lydian stone of Mac- 

 culloch (burnt shale), quartzite, and crystalline limestone. There are 

 few localities better adapted than the one in question for the study 

 of the series of changes, and especially of the gradual obliteration 

 of all traces of fossils in rocks, through contact metamorphism. 

 There can be little doubt that the Middle-Lias beds are of consi- 

 derable thickness in Ardnamurchan. 



At Bloody Bay, on the north side of the Island of Mull, beds of 

 sandstone of a bright red colour are found, which have been quarried 

 for building the lighthouse of Ru-na-Gal near at hand. The eroded 

 surface of these beds is seen to be directly covered by the Miocene 

 basaltic lavas. The most probable horizon to which to refer the beds 

 in question, which have not yielded a trace of fossil remains, would 

 appear to be that of the Torridon Sandstone, in which case the 

 locality is interesting as exhibiting the most southern exposure of 

 strata of that series. The peculiar sections at Tobermory, now about 

 to be mentioned, however, cause me to entertain some doubt as to 

 whether these red sandstones may not really be an altered condition 

 of the Scarpa Series. At present the question of the age of these 

 beds (as is not unfrequently the case with isolated patches of unfossili- 

 ferous strata in the Hebrides) must be regarded as still an open one. 



At Tobermory there appear, from underneath the basalts, beds of 

 sandstone of a deep red colour, and dark-coloured micaceous shales. 

 The former beds have been quarried on a small scale for building- 

 purposes ; the latter extend over the tide-way and are seen at low 

 water ; they have also been found in digging wells. These beds, 

 like those of Pabba, seem to have been first pointed out to geologists 

 by Hugh Miller, who, judging from mineral characters alone, re- 

 garded the red sandstones as the " Old Red." I have found in 

 these red sandstones, however, specimens of GrypJima obliqua, Goldf., 

 though fossils are certainly very rare in them ; and thus it is ren- 

 dered manifest that we have here some arenaceous beds in an altered 

 condition intercalated in the Middle Lias series. It is possible 

 that the strata already mentioned as occurring at Bloody Bay, with 

 others at Calve Islet and on the shores of Mull, two or three miles to 

 the southward, none of which have yielded fossils, may all be of the 

 same age. 



The dark micaceous shales of Tobermory, which are exposed only in 

 a small opening at the mill, as described by Hugh Miller, yielded 

 very numerous fossils, though not in a very good state of preserva- 

 tion. Mr. Hugh Miller, F.G.S., who has perseveringly explored the 

 rocks and studied the localities which his father's graphic pen has 

 rendered famous, has made a very considerable collection of fossils 

 from this locality ; and these he has most obligingly placed at my 



