Rev. O. Fisher—Thickness of Marine Deposits. 259 
parts, it seems proper, as we have done, to assign the whole to 
vertical elevation. Whether this was accompanied by crumpling 
or not would not affect the amount of elevation; but, seeing that the 
horizontal expansion at any given depth would be only one-third 
of the voluminal expansion at that depth, there could be but very 
little crumpling at any given place in the rocks, and there seems 
no means by which the crumpling could be localized. 
Our estimates, as already explained, have been made on the 
hypothesis that the expansion of the column does not commence 
until the sea has been filled up, instead of the two processes going 
on together, as in nature they would do; so that the rising sea- 
bottom would meet the falling sediment, and the sea get filled up 
with a less thickness of deposit, while only the balance of heat 
still required to make the flow steady, acting upon a less thickness 
of deposit than we have estimated, could be appealed to for the 
elevation of the plateau. 
A depth of 1000 fathoms is the limit of what Mr. Murray calls 
the Transitional area of the ocean ;' all beyond being classed as 
abysmal. It seems, then, that a mile is an excessive depth for the 
application of our calculations. 
On the whole our results do not appear to be favourable to the 
theory that elevated plateaus, and still less mountain ranges, can 
have been produced by the expansion of deposits owing to the con- 
sequent rise of isogeotherms, and that we must look in some other 
direction for the efficient causes of those features. What the writer 
believes these to be, will be found in chapter xxiii. of his “ Physics 
of the Harth’s Crust.” To describe them here would expand this 
paper to an undue length. 
Nore. 
Fic. 1 Fic. 2. 
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1 “On the Height of the Land and Depth of the Ocean,”’ Scottish Geographical 
Magazine, vol. iv. Jan. 1888. 
