148 GEOLOGY. 
first, and the various strata were formed in the order of their superposi- 
tion. You will observe that the strata marked from A to H are inclined, 
and, as these must have been deposited horizontally, they must therefore 
have been tilted up afterwards. We also see that the cause of their 
disturbance is the upheaval of the igneous mass I, which, issuing from 
beneath, has ruptured the strata previously flat, and overflowed part of 
the rocks where it rose to the surface. This upheaval has also thrown 
the strata at different angles, those to the right being more inclined than 
those to the left, and therefore forming a fault. We observe also that 
in the rocks to the left there occurs a great slip, for part stands at a 
different height from the rest. We can, however, easily trace each rock, 
.as, for instance, the coal-seam C, from the one side of the section to the 
other through both slip and fault. 
We also observe that after the trap eruption, the exposed rocks 
were subjected to long-continued water-action; for their outcrop is 
hollowed out into two valleys. After this period of denudation, the 
horizontal strata were deposited, and have not since been disturbed by 
voleanic action. We'see also that a great part of the trap is covered by 
this new deposit, so that what was once a hill, before this new rock was 
laid down, is now almost hidden beneath the surface. The horizontal 
undisturbed rocks have, however, been much worn away by water-action ; 
for deep valleys have been excavated in them, and the bed of a river still 
continuing the scooping out is seen at O. By looking at the highest and 
therefore last-formed deposit, we observe that it consists of gravel or silt. 
‘This, therefore, once formed the bottom of a lake or inland sea, where 
river-débris was deposited. This débris has been allowed to lie undis- 
turbed till elevated above the sea-level, after which it has been worn down 
by streams. Patches of it still remain on the hill-tops over various parts 
of the surface, as at the points marked N. 
2. Section with Aqueous Action alone, without Dislocation.—This second 
section (fig. 82) is of a part of the north coast of Norfolk, near the town of 
Cromer, and it is very striking and instructive. Let us see what we can 
learn from it regarding the history of the Norfolk shores. This section 
differs from the first in the entire absence of igneous action, for there is 
no displacement of any kind, its regularity being due to aqueous causes 
alone. 
The lowest rock (A) is chalk, in which we can see represented regular 
rows of flints. This chalk consists of the remains of shell-fish and other 
creatures, whose organisms are found in the flints. After the deposition 
of the chalk, the land was raised, and a great forest grew over the chalky 
soil, which is well suited for the growth of trees. The roots of the old 
oaks, with part of their stems, are still seen erect as they grew !—embedded 
in the mud that accumulated round them when afterwards submerged. 

