NOVA SCOTIA COAL-MEASURES. 
409 
on the ancient sands of the coal-measures was an air-breather, 
because its weight would not have been sufficient under wa¬ 
ter to have made impressions so deep and distinct. The 
same conclusion is also borne out by the casts of the cracks 
above described, for they show that the clay had been ex¬ 
posed to the air and sun, so as to have dried and shrunk. 
Nova Scotia Coal-measures. — The sedimentary strata in 
which thin seams of coal occur attain a thickness, as we 
have seen, of 18,000 feet in the north of England exclusive 
of the Mountain Limestone, and are estimated by Von De- 
chen at over 20,000 feet in Rhenish Prussia. But the finest 
example in the world of a natural exposure in a continuous 
section ten miles long, occurs in the sea-cliffs bordering a 
branch of the Bay of thmdy, in Nova Scotia. These cliffs, 
called the “South Joggins,” which I first examined in 1842, 
and afterwards with Dr. Dawson in 1845, have lately been 
admirably described by the last-mentioned geologist"^ in de¬ 
tail, and his evidence is most valuable as showing how large 
a portion of this dense mass was formed on land, or in 
swamps where terrestrial vegetation flourished, or in fresh¬ 
water lagoons. His computation of the thickness of the 
whole series of carboniferous strata as exceeding three miles, 
agrees with the measurement made independently by Sir 
William Logan in his survey of this coast. 
There is no reason to believe that in this vast succession 
of strata, comprising some marine as well as many fresh-water 
and terrestrial formations, there is any repetition of the same 
beds. Tliere are no faults to mislead the geologist, and cause 
him to count the same beds over more than once, while some 
of the same plants have been traced from the top to the bot¬ 
tom of the whole series, and are distinct from the flora of the 
antecedent Devonian formation of Canada. Eighty-one seams 
of coal, varying in thickness from an inch to about five feet, 
have been discovered, and no less than seventy-one of these 
have been actually exposed in the sea-cliffs. 
In the annexed section (Fig. 439), which I examined in 1842, 
the beds from c to ^ are seen all dipping the same w^ay, their 
average inclination being at an angle of 24° S.S.W. The ver¬ 
tical height of the cliffs is from 150 to 200 feet; and between 
d and^—in which space I observed seventeen trees in an up¬ 
right position, or, to speak more correctly, at right angles to 
the planes of stratification—I counted nineteen seams of coal, 
varying in thickness from two inches to four feet. At low 
tide a fine horizontal section of the same beds is exposed to 
view on the beach, which at low^ tide extends sometimes 200 
Acadian Geology,'2d edit., 1868. 
18 
