132 Revieios — Prof. GeiJcie's Geological Map of Scotland. 



the so-called Lower and Middle Old Eed Sandstones south of the 

 Grampians are regarded as constituting a single formation ; the 

 unconformity visible between Tinto and the Pentlands being looked 

 upon as a local feature dependent upon the igneous action so rife 

 at that period. In the face of the evidences he has adduced, it is 

 impossible to resist the conviction that this arrangement, so far as 

 these beds are concerned, is the one which is most convenient and 

 most in accordance with the order of nature ; and in these respects 

 it must be looked upon as a decided gain. His second conclusion, 

 namely, that the Caithness Flagstones are, in all probability, of con- 

 temporaneous age with the admitted Lower Old Eed Sandstones of 

 Perth and Lanark, is of too sweeping a nature to be so readily con- 

 ceded. The author seems fully aware of this fact; for though the 

 beds are coloured as of Lower Old Eed age upon the map, the 

 original lettering, expressive of their Middle Old Eed age, is still 

 retained. 



His third and most important conclusion, that everywhere 

 throughout Scotland the so-called Upper Old Eed Sandstone reposes 

 with a violent unconformability upon all the underlying rocks, and 

 shades upwards into the basal beds of the Carboniferous, is made to 

 do great service. This subformation is here coloured as if of Old 

 Eed Sandstone age, but is bracketed with the Carboniferous. The 

 detection of marine fossils characteristic of the Carboniferous Lime- 

 stone in red beds far inferior in geologic position to the theoretical 

 base of the Cement-Stone group, or Upper Calciferous Series, of 

 Arran, is very naturally regarded as of immense weight, and is held 

 as sufficient in itself to demonstrate the co-existence of the typical 

 Upper Old Eed Sandstone fauna with that of the Carboniferous 

 Limestone. The red or lower division of the Calciferous Sandstone 

 Series is therefore no longer united to the upper or grey division, 

 but is grouped with the underlying and lithologically similar forma- 

 tion of the Upper Old Eed Sandstone. 



This change we believe to be wholly uncalled for, especially in 

 the present stage of the Devonian controversy, when every step 

 should be made with the greatest circumspection. All who have 

 interested themselves in this question are well aware that in the 

 south-west of Ireland, the Upper Old Eed Sandstones are separated 

 from the lowest Carboniferous Limestones by the enormous mass of 

 the Coomhoola Series and the Lower Limestone Shales. These 

 rapidly thin out as we proceed to the north, until the Carboniferous 

 Limestone rests at once upon Silurian rocks. Still further to the 

 north the Limestone itself is divided into an upper and lower 

 portion by the intercalation of the sandstone beds of the Calp. 

 Almost upon the same parallel the interesting researches of Mr. 

 Goodchild have made it evident that the Carboniferous Limestone of 

 Westmorland is similarly divided into an Upper and Lower portion 

 by the gradual intercalation of the Ash Fell Sandstones, etc., with 

 a few calcareous bands. The arenaceous rocks thicken out as we 

 pass northward to Cross Fell, while the underlying lower portion of 

 the Carboniferous Limestone simultaneously thins away till the 



