284 Correspondence—Mr. John Gunn. 
The rock then clearly was not very rare in this part of Anglesey. 
These exhibited some varietal differences. The author gave some 
details of their microscopic structure, and an analysis of one identical 
with the Pen-y-carnisiog rock, kindly made for him by Mr. J. A. 
Phillips, F.R.S., from which it appeared that this British picrite cor- 
responds fairly well with the picrite of Schriesheim in the Odenwald, 
to which in other respects it bears so close a resemblance. Mr. J. J. 
H. Teall recently called the anthor’s attention to a rock which he had 
collected on Little Knott, east of Bassenthwaite, which appeared to 
him to resemble the description of the Anglesey picrite. ‘he author 
had examined a series of specimens from that locality, and found that 
macroscopically and microscopically there was a marked resemblance, 
while the per-centages of silica and magnesia were not very different. 
He thought, then, it was very probable that the Anglesey boulders 
came from the Little-Knott district. 
COS! @ ia a saNiC mar 
er a 
M. GAUDRY ON THE CLIMATE OF THE QUATERNARY PERIOD. 
Str,—I beg to call your attention to M. Albert Gaudry’s valuable 
contribution to geological science.! It appears to me to establish 
the correlation between the Glacial and Interglacial formations of 
this country and near Paris. The reappearance of the Hippopota- 
mus, and the return of warm period in both, if true, are of the | 
highest interest. JOHN GUNN. 
All geologists know that in England there is, above the Forest- 
bed, the Boulder-clay, which represents that which is called the 
great Glacial epoch. We cannot study the Cliffs of Norfolk, near 
Cromer or Happisburgh, without being impressed with the import- 
ance of the deposits of Boulder-clay. We were ignorant up to the 
present time of what had passed at Paris during the continuance of 
the Glacial phenomena, which English savants have so well de- 
scribed in Norfolk, in Wales and Scotland. 
To this day, I conceive that the bed on the summit of Montreuil, 
about 100 métres high, is one of the representatives of the great 
Glacial Epoch of the Boulder-clay. The presence of the Reindeer 
ought not to cause astonishment, for that animal is pointed out in 
Scotland beneath the Boulder-clay. 
If my supposition be correct, with these paleontological data, the 
history also of the Quaternary period may be traced in the Paris basin. 
1. Phase Warm—the deposits of St. Prest—Elephas meridionalis—transition be- 
tween the Tertiary and the Quaternary Periods. 
2. Great Glacial Phase —deposit on the summit of Montreuil, at the height of 100 
métres—herds of Reindeer, Rhinoceros tichorhinus. 
3. Phase Warm—diluvium e/ow Montreuil at the height of 53 métres—Hippopotami, 
Cervus, Rhinoceros Merckii, Elephas antiquus. Possibly the Fig-trees and the 
Laurels of La Celle, near Moret, pointed out by MM. Chouguet, de Saporta, 
and Tournouér, belong to the same phase. 
Phase Temperate—Diluvium of the low levels of Grenette and of Levallois-Perrots, 
at the height of 30 métres—Dlephas primigenius, Rhinoceros tichorhinus, and 
the Reindeer have returned. A mixture of warm and cold species. 
5. A sudden return of cold—age of the Reindeer ; the Riioceri have disappeared. 
6. Present age—age of the ‘‘ Polished stones.”’ 
1 «Sur un gisement de Rennes auprés de Paris,” par M. A. Gaudry. 
nS 
