CHAPTER VI. 
The Lines of the Geographer rarely right Lines. — These last, how- 
ever, always worth looking at when they occur. — Striking Instance 
in the Line of the Great Caledonian Valley. — Indicative of the 
Direction in which the Volcanic Agencies have operated. — Sec- 
tions of the Old Red Sandstone furnished by the Granitic Emi- 
nences of the Line. — Illustration. — Lias of the Moray Frith. — 
Surmisings regarding its Original Extent. — These lead to an Ex- 
ploratory Ramble.— Narrative. — Phenomena exhibited in the 
course of half an hour’s Walk. — The little Bay. — Its Strata and 
their Organisms. 
Tue natural boundaries of the geographer are rarely de- 
scribed by right lines. Whenever these occur, however, the 
geologist may look for something remarkable. There is one 
very striking example furnished by the north of Scotland. 
The reader, in consulting a map of the kingdom, will find that 
the edge of a ruler, laid athwart the country in a direction 
from south-west to north-east, touches the whole northern 
side of the great Caledonian Valley, with its long, straight 
line of lakes; and onwards, beyond the valley’s termination 
at both ends, the whole northern side of Loch Eil and Loch 
Linnhe, and the whole of the abrupt and precipitous northern 
shores of the Moray Frith, to the extreme point of Tarbat 
Ness—a right line of considerably more than a hundred 
miles. Nor does the geography of the globe furnish a line 
better defined by natural marks. There is both rampart and 
fosse. On the one hand we have the rectilinear lochs and 
lakes, with an average profundity of depth more than equal 
to that of the German Ocean, and, added to these, the rec- 
tilinear lines of frith; on the other hand, with but few inter- 
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