British Association. 227 
with the existence and preservation of organic forms, and that these 
silicates have resulted, not from subsequent metamorphism at great 
depths, but from reactions going on at the earth’s surface, as he has 
already pointed out in published papers, with regard to the deposition 
of silicates from natural waters,—the Tertiary beds of sepiolite with 
neolite, and the formation of glauconite (hydrous silicate of protoxide 
of iron and potash, often with alumina), in all ages from the Silurian 
upwards, especially in company with organic forms (Foraminifera, 
&c.), as observed by Ehrenberg, Mantell, Bailey, and Pourtales. 
When dissolved silica comes in contact with iron-oxide rendered 
soluble by organic matter, the resulting silicate (glauconite) is formed 
in the cavities of minute sea-shells; so, probably, the magnesian sili- 
cates associated with the Hozoén may have been formed, Mr. Hunt 
suggests, by the direct action of alkaline silicates, either dissolved in 
surface-water or in those of submarine springs, upon the calcareous 
and magnesian salts of the sea-water; and he is now conducting 
experiments towards the elucidation of the facts. 
On THE MrAsurE or Groxocican Timm py Natura Curonometmrs.* By Pro- 
fessor Putitries, F.R.S., F.G.S. 
ISTINGUISHING, in the first place, between the history of 
operations in the sea and on the land, by which the succession 
of ancient phenomena is determined, from the attempts to ascertain, 
first the relative, and finally the absolute chronology of these events, 
the author noticed several orders of natural effects which, being 
traceable through the later geological periods, and still in progress, 
seemed the fittest to be employed in the measure of Cenozoic time. 
Examples are found in the action of streams wearing away their 
channels, or depositing sediment ; in the formation and growth of 
peat-moor ; in the filling up of lakes ; and, finally, in the accumu- 
lation of detritus in conical mounds at the foot of precipices by fall- 
ing of rocks or torrents of water. ‘The last case was illustrated by 
drawings, and a description of the remarkable mounds of La Tiniére 
on the Lake of Geneva, near Villeneuve, which have been investigated 
by M. Morlot. At this place one of the mounds, the least ancient, 
has been cut through by the railway to a depth of between 20 and 
30 feet. The section exposes the materials usually found in such 
mounds—large and small pebbles and sand; but, in addition, three 
bands of loamy nature, six to eight inches thick, are seen to range 
parallel to the general surface, one 4 feet below the surface, another 
10 feet, the third 19 feet. The bands contain charcoal, and have 
rather the aspect of vegetable earth, in part stained yellow. With 
the upper one were found Roman reliquize—fragments of tiles and a 
coin ; the middle one yielded no such objects, but some bronze ar- 
ticles ; the lower one, coarse pottery, also fragments of bones of 
men and animals. Professor Phillips was so fortunate as to obtain 
from this lowest band, by his own research, a portion of cranial 
bone, which, by the help of Mr. C. Robertson of the Oxford Museum, 
* “The Reader,’ Oct. 1, 1864. 
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