32 A. Tylor on Changes of the Sea- Level, eic. 
soon, however, as any disturbing causes interrupt the supplies of 
new material, the sand and shingle beaches dependent upon them 
must soon disappear ; and in fact the termination of every beach 
will be at that point where the waste and abrasion by breaker- 
action are balanced by the supply of pebbles and sand drifted from 
other places. Although it appears clear that only the detritus ob- 
tained from cliffs above high-water mark need be taken into cal- 
culation, yet I regret to find that scarcely any data of this kind 
exist, and therefore it is not possible to ascertain the probable 
effect upon the sea-level that is being produced by the detritus so 
derived. In the same manner the per-centage of soluble salts in 
the water of the few large rivers of which notes have been pub- 
lished has not been given separately from the per-centage of mat- 
ter in suspension, and therefore we are in ignorance of the sup- 
plies that are annually introduced into the ocean from the forma- 
tion of submarine deposits from materials dissolved in the sea- 
water. When therise in the sea-level from the effect of alluvium 
brought in suspension by rivers was bau considered, I supposed 
that that cause alone might produce an elevation of one foot in 
54, years; but in order to make some allowance for the simi- 
lar effects that must be produced by the introduction into the 
ocean of materials from above high-water mark on n coast- -lines* 
by breaker-action, and also by the formation of submarine depos- 
its from materials which were brought into the ocean in solution, 
I now propose to consider that all these causes together might 
produce an elevation of the sea-level equal to one foot in AO, 000 
oe or hae inches in 10,000 years. 
win has remarked, that ‘the knowledge of any result, 
which, vith sufficient time allowed, can be produced by causes, 
though appearing paste improbable, i is valuable to the geolo- 
gist, for he by his deals with centuries and thousands of 
years as others ie: wih minutes.” For these reasons, even if, 
upon further bie er it should be found that the true rise in 
the sea-level is much less than three inches in 10,000 years (in 
periods ubdistarbed by subsidences and elevation), yet it may 
still be an important element in accounting for those changes 
which we are now about to consider 
(To be sees) 
* The rough estimation of the a of coast-line, kindly supplied by Mr. A- 
Jabioatni, (Noy. 1852), is as follow ae by 
+s me English statute miles 
(60 toa degree.) (694 to a degree.) 
Europe, +e cane AHROO 20,425 
Asia, - . - - 80,800 34,825 
Africa, - - - 14,000 16,625 
Amer - “ 37,600 44,656 

99,600 116,581 


