CHAPTER XVm 
STKUCTUllE AND ARRANGEMENT OF THE LOWER OLD RED SANDSTONE 
VOLCANIC ROCKS IN THE FIELD 
We have now to consider the manner in which the various volcanic 
products have been grouped around and within the orifices of ‘tischai e 
The first feature to arrest the eye of a t^^^^d geo ogist 
them as they are displayed in one of the ranges o 
is the bedded aspect of the rocks. If, for example, he looks eastvaid from 
the head of tlie Firth of Tay, he marks on the right hamh ’ 
many miles through the county of Fife, a succession ot parallel escaipments, 
of which the steep fronts face northwards, while their long dip-slopes 
On his left hand a similar hut higher series 
„t escanmients. .^etching far eaaUv.rda into Forltehire, ‘"“"S'' 
of the Sidlaw Hills, repeats the same features, hut in opposite diicc .. 
If t iU illuvial plain of the Forth, near- Stirhng, and looks 
towards the north, he 
can 
trace bar after bar of brown rock and grassy 
slope rising from base to summit of the western end of the OchT HiUs. 
If Lain from any height on the southern outskirts of the city of Edinbui , 
he fets his eye Lge along the north-western front of the chain of he 
Pentland Hills, especially towards evening, he can ^lie f^ve 
banding as a conspicuous feature on each successive hill that mounts abov 
the plain Or if, as he traverses the west of Argyllshire, he come 
sight^of the uplands of Lome, he at once recognizes the terraced contours o 
the hills betwLn Loch Awe and the western sea, presenting so strange a 
contrast to tile rogged and irregular outlines of the more ancient scliiat and 
granite mountains all around (see Fig. 99). 
i. BEDDED LAVAS AND TUFFS 
On a iieai-er insi.eotio.i, the dominant topigrnphical featuri* am fo^d 
to correspond with a well-marked stratification of the whole “““ 
Where two sheets ot andesite are separated by layers ol tuff. “ 
conglomerate, a well-marked hollo, will o ten be found to ^ 
junction-line; but even where tlie lavas lollow each other without such 
