14 On the Red Sandstone Formation. (Jury, 
‘with an extensive series of newer rocks. It is distinctly stratified'¥ 
‘and the strata vary from the horizontal to the nearly perpendicular 
position. The strata are sometimes waved, sometimes disposed in a 
concentric lamellar manner, but are more frequently straight. 
Sometimes vertical strata are to be seen meeting others which are 
‘in/a horizontal position, and occasionally vertical swata are contained 
in masses of nearly horizontal or slightly inclined strata. Occasionally 
the strata in a small district appear disposed in every possible’ posi- 
tion; and at first sight suggest to us the idea either of great original 
inequalities, or of violent action on the strata after their formation; 
but which, upon more careful examination and consideration, would 
seem rather to intimate that the whole mass of strata is composed 
of a series of distinct concretions, in each of which the layers or 
strata vary more or less in position. it 31 
Red sand-stone contains many different rocks, either in Beag 
mountain-masses, or veins. The following are the principal kinds 
‘of rock I have met with in the red sand-stone of Scotland. 
1. Red-coloured Slate-clay.—This rock occurs in beds that vary 
in thickness from a few inches to several fathoms. It is sometimes 
so highly impregnated with calcareous earth as to pass into marl. 
Its red colour is sometimes variegated with stripes, layers, and cir- 
cular portions of a green colour. It passes sometimes into clay+ 
stone, and sometimes into clay-iron-stone. It occurs in Salisbury 
Craigs, near Edinburgh ; Pentland and Ochre Hills ; Isle of Arran ; 
en near Saltcoats ; Drumfrieshire ; Angus-shire, &e.) >? 
2. Clay-stone.—This mineral occurs in beds that vary in thick+ 
ness from an inch to several yards. It alternates with the preceding 
rock, and also with red sand-stone, and some other rocks subordi- 
nate to it. It occurs in Salisbury Craigs, Pentland and Ochil Hills, 
Arran, Ayrshire, Dumfrieshire, Angus-shire, &e. 
3. Clay-iron-stone.—It occurs in layers, or in irregular shaped 
masses, generally included in slate-clay. It is a frequent mineral 
in many red sand-stone districts, as in the Island of Arran, Dum-+ 
frieshire, Lothians, Angus-shire, &c. 
4. Trap Tuff—This singular and interesting rock occurs in the 
red ’sand-stone in beds, which are frequently of great thickness. It 
passes into clay-stone and red sand-stone. It is by no means an 
uncommon rock in several of the red sand-stone districts of this 
country, as in the Lothians, Arran, Angus-shire, &c. 
5. Amygdaloid.—This rock, like the trap tuff, occurs in great 
beds or hills connected with the red sand-stone, and occasionally 
imbedded cotemporaneous masses of it are met with in the sand- 
stone. dt passes into the tuff and sand-stone. It is one of the 
rocks of the red sand-stone districts in East Lothian and Mid-Lo- 
thian, Ishands of Bute and Arran, Angus- shire, &e. 
106. Basalt.—This rock occurs in beds and veins in the red sand- 
stone of Bute, Arran, Ochils, Pentlands, Lothian, Angus-shire, &e. 
b27s Clink=stone.—This beautiful rock is abundant in several red 
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