Revieios — Prof. Geikie^s Geological Map of Scotland. 133 



arenaceous rocks rest immediately upon the Silurians. The Scottish 

 Calciferous Sandstones are admitted to be actually the northerly 

 extension and expansion of these red and grey sandstones of 

 Westmorland. In other words, they are simply arenaceous repre- 

 sentatives of the Lower or central portion of the English Carbo- 

 niferous Limestone. The greater abundance of these coloured 

 sandstones in the Carboniferous rocks of Arran is in exact corre- 

 spondence with the general behaviour of the strata of this system in 

 Britain generally ; and the presence of the Carboniferous Limestone 

 fossils, even in their very lowest beds, instead of being matter for 

 astonishment, and an argument for a local revolution in our present 

 plan of classification, is, on the other hand, so natural and inevitable 

 under our present ideas of the relationships of the Upper Old Red 

 and the Carboniferous, that, from an a priori point of view, it is almost 

 impossible to conceive how the facts should have been otherwise. 



Of the Carboniferous formation itself, four divisions are noted by 

 the author — the Calciferous Sandstones, the Carboniferous Lime- 

 stone, the Millstone Grit, and the Coal-measures. The first of these, 

 under the arrangement already described, includes only the Upper 

 or Cement-stone division of the original Calciferous rocks. The 

 limits of these sub-groups are accurately traced through the whole 

 of the Central Valley. The disputed coal-field of Canobie is fixed 

 as belonging to the true Coal-measures, and the wide sheet of Car- 

 boniferous rocks in Eskdale, etc., has been removed to the Calci- 

 ferous Sandstones. 



The Permian areas of Annan, Dumfries, Thornhill and Moffat, 

 have now for the first time their limits correctly laid down. No 

 alteration is made in the outline of the Triassic district in the neigh- 

 bourhood of Elgin ; but the small patch of rocks of this age dis- 

 covered by Professor Judd near Dunrobin is indicated upon the 

 map, and the complete dissipation of the doubts regarding the 

 actual presence of this formation in Scotland is distinctly acknow- 

 ledged in the removal of the note of interrogation from its title in 

 the margin. 



Indeed, the masterly papers of Professor Judd have proved a mine 

 of wealth to the author. As far as possible all the more important 

 details worked out by him are here inserted. The Jurassics of 

 Sutherland and the Western Isles are coloured in two divisions ; the 

 Cretaceous rocks find for the first time in the map of Scotland 

 their special place and colour; and the geological structure of the 

 volcanic region of Mull and the adjacent coasts is delineated with a 

 minuteness and clearness, which, when we consider the small scale 

 of the map, is almost marvellous. 



Glacial and post-Tertiary geology generally comes in for a full 

 share of attention. Over the whole country are arrows showing the 

 local direction of the glacial strite. The main streams of glacial 

 debris and morainic matter are dotted in over the Lowlands, and 

 upon both flanks of the Grampian range. The raised beach, the 

 fertile carse of alluvium and the barren tract of blown sand, are 

 separately indicated, each by its special and appropriate shade of 

 colour. 



