Some of these formations, which are represented in England by thin beds, are thousands of feet in thickness on the Continent.
Though it must be admitted that the denudation of the Weald has been a mere trifle, in comparison with that which has removed masses of our palaeozoic strata, in parts ten thousand feet in thickness, as shown in Prof.
Forbes, we may conclude that the bottom will be inhabited by extremely few animals, and the mass when upraised will give a most imperfect record of the forms of life which then existed; or, sediment may be accumulated to any thickness and extent over a shallow bottom, if it continue slowly to subside.
I may add, that the only ancient tertiary formation on the west coast of South America, which has been bulky enough to resist such degradation as it has as yet suffered, but which will hardly last to a distant geological age, was certainly deposited during a downward oscillation of level, and thus gained considerable thickness.
Within this door is the staircase which ascends straight through the thickness
of the wall, not communicating with the room on the first floor, in whose centre is the opening to the dungeon.
"If we follow the usual proportion," replied Morgan, "a diameter of 108 inches would require sides of two feet thickness, or less."
The problem, therefore, is this-- What thickness ought a cast-iron shell to have in order not to weight more than 20,000 pounds?
"The sides will require a thickness of less than two inches."
Forbes, in a greater depth of water than from 40 to 250 feet; but they are now covered with sea-deposited strata from 800 to 1000 feet in thickness
: hence the bed of the sea, on which these shells once lived, must have sunk downwards several hundred feet, to allow of the accumulation of the superincumbent strata.
`Nor, having only length, breadth, and thickness, can a cube have a real existence.'
`Clearly,' the Time Traveller proceeded, `any real body must have extension in FOUR directions: it must have Length, Breadth, Thickness, and--Duration.
That Space, as our mathematicians have it, is spoken of as having three dimensions, which one may call Length, Breadth, and Thickness, and is always definable by reference to three planes, each at right angles to the others.