74 
ELEMENTS OF GEOLOGY. 
similar position in the Swiss Alps, he remarked that the 
pebbles, being for the most part of an oval shape, had their 
longer axes parallel to the planes 
of stratification (see Fig. 54, on 
the preceding page). From this 
he inferred that such strata must, 
at first, have been horizontal, each 
oval pebble having settled at the 
bottom of the water, with its flat¬ 
ter side parallel to the horizon, for 
the same reason that an egg will 
not stand on either end if unsup¬ 
ported. Some few, indeed, of the 
rounded stones in a conglomerate 
occasionally afford an exception to 
the above rule, for the same reason 
that in a river’s bed, or on a shin¬ 
gle beach, some pel)bles rest on 
their ends or edges; these having 
been shoved against or between 
other stones by a wave or current, 
so as to assume this position. 
Anticlinal and Synclinal Curves. 
—Vertical strata, when they can 
be traced continuously upward or 
downward for some depth, are al¬ 
most invariably seen to be parts 
of great curves, which may have a 
diameter of a few yards, or of sev¬ 
eral miles. I shall first describe 
two curves of considerable regu¬ 
larity, which occur in Forfarshire, 
extending over a country twenty 
miles in breadth, from the foot of 
the Grampians to the sea near Ar¬ 
broath. 
The mass of strata here shown 
may be 2000 feet in thickness, con¬ 
sisting of red and white sandstone, 
and various colored shales, the 
beds being distinguishable into 
four principal groups, namely, No. 
1, red marl or shale; No. 2, red 
sandstone, used for building; No. 3, conglomerate; and No. 4, 
gray paving-stone, and tile-stone, with green and reddish 
shale, containing peculiar organic remains. A glance at the 
