48 . '. + Corvespondence—Rev. O. Fisher. 
and the total available quantity of water percolating into the sandstone. 
ee to about 300 millions. 
‘‘ Notes on the Raised Beaches of Taltal (Northern Chile). ad 
Oswald Hardey Evans, F.G.S. 
~The town of Taltal is situated partly on the dry bed of a broad 
river and partly on a gently inclined plain that fringes the bays of 
the coastal ranges far to the northward, and runs up the valleys to 
a considerabie altitude and distance from the coast. The material of 
this plain consists of sands and well-rounded gravel derived from the 
rocks of the adjacent hills, mingled with shells and some isolated 
boulders of considerable size. The formation is impregnated with 
salt, and there protrude through it curiously weathered remnants of 
former stacks and islets. The plain rises in terraces, the highest of 
which are somewhat obscure, and sometimes portions of these higher - 
terraces are preserved in the stacks and islets. A second coastal shelf 
also occurs, marked by a line of shallow caverns, some excavated in 
igneous rocks. Some, at least, of the shell-accumulations associated 
with the plain contain pottery, and are associated with Indian kitchen- 
middens, but the beds of shells in the gravel, containing occasionally 
whale-bones, give satisfactory evidence of the marine origin of the 
terraces. Some of these shells are replaced by crystallized brine, and - 
calcium sulphate occurs in some sections. Profound ravines (quebradas) 
oecur in the massive rocks bordering the plain, although the climate is 
now so dry that rain-erosion is practically non-existent. 
CORRESPONDENCE. 
THICKNESS OF LAND-ICE. 
Srr,—I have not followed the discussion to which Mr. Loses 
alludes in his letter of November 7th, but I should be thankful to be 
allowed to make a remark upon the final sentence, where he says that 
‘“the evidence for the past and present existence of ice of greater 
thickness than 1,600 feet is so strong that physicists who wish to 
apply this limitation may be advised, in their own interest, to revise 
their calculations.” 
I published a paper ‘‘On the Thermal Conditions and Stratification 
of the Antarctic Ice” in the Phil. Mag. for June, 1879, in which 
I arrived at the conclusion that supposing the surface at zero Fahr., 
after the ice had accumulated to the thickness of 740 feet (about), 
it would begin to melt at the bottom owing to the pressure ; but 
I concluded (p. 385) that ‘No certain limit can be imposed upon the 
thickness to which ne ice might accumulate, provided the snowfall be 
more than sufficient to counterbalance the melting at the bottom.” 
I do not know who the physicists may be to whom reference is 
made in Mr. Lamplugh’s letter, but as I have corresponded with 
Professor Schwarz upon this subject I have thought it as well to 
show that for one my calculations do not require revision. 
QO. FIsHER. 
GRAVELEY, HunTINGDON. 
December 3rd, 19066 
