826 The American, (ieologi^t. N.-vember, xm-x 
Stu<ltfsof Mail- Ohirier, Alushi. Harry Fiem)IN(: Keid (Nat. Geog, 
Mag. IV, Mch. 21, 1892). Some of Mr. KeicVs concluaions disagree largely 
with previous studies upon the same ulacier. He finds the greatest ad- 
vance to have been seven feet two inches daily, and the smallest four 
inches. Professor Wright's greatest advance, as measured in 188K, was 
73 ft. {Ice Age in N. A. p. 50): however, if we assume both measurements as 
correct, a change of climatic conditions may account for the verj^ great dif- 
ference. The erosion is estimated at three ((uartors of an inch per an- 
num. 
Mr. Cusliiug, the geologist of the expedition, I'ouud the exposed rocks 
to consist of limestone, argillite, <iuartz-diorite and diorite; and Dr. 
Williams' microscopic examinations revealed several diorites, porphyry, 
porphyrites, gabbro (troctolite not from the glacier) and diabase. Dr. Her. 
rick contributes a "microscopical examination of wood from the buried 
forest,*' pp. 75 78; Mr. Rowlee, a list of plants and finally Mr. Reid, meteor- 
ological and magnetic observations and suggestions to future ob- 
servers. 
Gibf) I If nr— par Pail Chofhat. (Bull. Soe, G<^ol. France.) This in- 
teresting contribution is cliieHy a criticism of the report on the geology 
of Gibraltar made some time ago by Ramsay and Geikie, who, accord- 
ing to M. Choffat, were unable, on account of artificial obstruction, to 
view the best exposed portions of the rock, which are now inaccessible. 
These gentlemen obtained but a few specimens of a single species of 
Rhynchonella, which was determined by Messrs. Etheridge and David- 
son to be very near H. eoncinna Sow., thereby placing the rock in the 
same horizon as the Great Oolite and Corubrash of England. 
M. ChofEat then alludes to the excellent report upon this celebrated 
rock by Smith, made many years ago, in which these remains are de- 
scril)ed as R. ti'trccdra Sow., Lias. M. Choftat has been able to examine 
this species and also those collected by Ramsay and Geikie and finds 
they are identical. As this species {tetni'drn) occurs in the Alpine Lias, 
and as the author has lately discovered the same in Portugal he sees no 
reason for changing the age, as proposed by the two English observers. 
He therefore contends tliat the age (Lias) proposed b}' Smith is the proper 
one. 
On Nepheline roclix ill Braxil, Part ii. Orvilt.e A. Dekbv. (Quart. 
.Tour. Geol. Soc. May, 1891.) In this paper the author comes to the 
conclusion that the Tingua peak, in the midst of an area of gneiss, com- 
posed as it is of orthoclase-nepheline rocks some of which arefragmen- 
tal tuffs though hardly distinguishable from plionolite flows, is a pc/v/- 
sitic or superiviposed mountain, according to the nomenclature of Von 
Richthofan. This is but one of a number of localities in which the 
same features and the same rocks occur. Its age is unknown, but later 
sedimentary rocks containing similar eruptive rocks are near, and in 
the vicinity are Carboniferous fossils. It would appear therefore that 
the peak may be a renmant of a volcanic cone left after the denudation 
