700 J. W. JTTDD ON THE SECONDARY ROCKS OF SCOTLAND. 



obscure all this part of the great cliff-section, that, as in the opposite 

 coast at Applecross, we have marine strata consisting of compact, 

 shelly, and oolitic limestones of a pale blue colour, occasionally- 

 abounding with corals, which alternate with thick masses of littoral 

 origin, consisting of shales, sandstones, and grits, with thin and 

 inconstant seams of coal in their midst. 



Very interesting for comparison with the section of Infralias strata 

 of Applecross is that exposed along the north shore of Strath between 

 Lussay and Obe Breakish. The beds are only seen in a series of 

 shore-reefs ; and their thickness can be estimated only roughly. No 

 estuarine strata are found at this horizon in Skye ; but the highest 

 member of the series consists of beds of coarse white sandstone, ex- 

 hibiting in its false-bedding and other characters clear evidence of 

 having been deposited under estuarine conditions. These sandstones 

 are quite destitute of fossils, and immediately underlie and pass up 

 into the shales and sandstones of the BucJclandi- or Zzma-series. 



The Strath section is as follows : — 



feet. 



(1) White sandstone, occasionally containing quartz pebbles, and 



passing into conglomerates. No fossils yet found 30 



(2) The Obe-Breakish limestones and shales. One of the upper beds is 



crowded with Thecosmilia Martini*, E. deFrom.,and forms a veri- 

 table coral reef. Ostrea ( Terquemia) arietis, 0. irregularis, a gi- 

 gantic Pinna, and many univalves also occur at the same horizon. 

 The limestones are usually compact, but occasionally are very 

 shelly, being almost made up of masses of Ostrea irregularis : 

 they alternate with bands of dark blue shale. These beds are 

 repeated by faults at Brcadford (where they are burnt for lime), 

 and appear at many points inland and on the south side of the 

 district of Strath, where they are usually much altered by igne- 

 ous intrusions, passing into saccharine limestone and ophicalcite. 

 The thickness of this set of beds cannot be less than 1 50 



(3) Calcareous sandstones, the surfaces of the beds of which are 



covered with casts of Cardinia concinna 7 to 8 



(4) Another coral reef, formed of Isastrcea Murchisonce, underlain by 



a compact bed of limestone 3 



(5) Greenish and chloritic sandstone, with irregular ferruginous 



concretions passing down into calcareous grit, and then into 

 hard subcrystalline limestone containing only very obscure traces 

 of shells ( Ostrea irregularis, Miinst.). 



Only about 9 feet of these beds are exposed ; and they lie directly 

 upon the thin representative of the Poikilitic strata of this place 

 (see page 691)f . 



* I am indebted to Prof. P. M. Duncan for examining the corals from the 

 west coast of Scotland. 



t As one of the most serious and apparently best-circumstantiated charges 

 against the good faith of Dr. Macculloch has been based on a criticism of his 

 description of the strata at this point, it may be as well to examine this charge 

 in detail. We are told that Macculloch commences the line of junction of the 

 Secondary beds and Torridon Sandstone " at the head of the long narrow creek of 

 Obe Breakish, instead of at the village of Lussay, thus colouring as Red Sand- 

 stone a space two miles in length, which is actually Lias " (Quart. Journ. Geol. 

 Soc. vol. xiv. 1858, p. 3). But an examination of Macculloch' s map, which is 

 taken from a very old and imperfect chart (the best basis he could obtain for his 

 geological observations), will convince any unprejudiced observer that the error 



