12 THE OLD RED SANDSTONE. 
of Ross-shire, where the Old Red Sandstone leans at a high 
angle against the prevailing Quartz Rock of the district, to 
where, on the southern skirts of Mid-Lothian, the Mountain 
Limestone rises amid the coal. I have resided one season on 
a raised beach of the Moray Frith. I have spent the season 
immediately following amid the ancient granites and contort- 
ed schists of the central Highlands. In the north I have laid 
open by thousands the shells and lignites of the Oolite ; in the 
south I have disinterred from their matrices of stone or of 
shale the huge reeds and tree ferns of the Carboniferous pe- 
riod. I have been taught by experience, too, how neces- 
sary an acquaintance with geology of both extremes of the 
kingdom is to the right understanding of the formations of 
either. In the north, there occurs a vast gap in the scale. 
The Lias leans unconformably against the Old Red Sand- 
stone; there is no Mountain Limestone, no Coal Measures, 
none of the New Red Marls or Sandstones, Under or Upper. 
There are at least three entire systems omitted. But the upper 
portion of the scale is well nigh complete. In one locality 
we may pass from the Lower to the Upper Lias, in another 
from the Inferior to the Great Oolite, and onward to the Ox- 
ford Clay and the Coral Rag. We may explore, in a third 
locality, beds identical in their organisms with the Wealden 
of Sussex. Ina fourth we find the flints and fossils of the 
Chalk. The lower part of the scale is also well nigh com- 
plete. The Old Red Sandstone is amply developed in Moray, 
Caithness, and Ross ; and the Grauwacke, in its more ancient 
unfossiliferous type, rather extensively in Banffshire. But to 
acquaint one’s self with the three missing formations, — to 
complete one’s knowledge of the entire scale by filling up 
the hiatus, — it is necessary to remove to the south. The 
geology of the Lothians is the geology of at least two thirds 
