MARCH 29, 1901.] 
SECTION OF GEOLOGY AND MINERALOGY OF 
THE NEW YORK ACADEMY OF SCIENCES. 
AT the meeting of the Section on February 
-18, 1901, the following program was pre- 
sented : 
“The Granite of Barre, Vermont,’ by George 
I. Finlay. The speaker described the occur- 
rence of the granite as a single intrusion 
through the country rock, which is a biotite 
schist, in the southeastern portion of Barre 
township. Many inclusions of the schist are 
found in the granite, and this rock has almost 
surrounded other masses of the schist which 
remain in place, with their original strike and 
dip unchanged. The speaker employed a 
series of original lantern views to illustrate the 
character of the jointing, the ‘ onion structure,’ 
and the zones of shearing, together with cer- 
tain large systems of joints, standing at right 
angles to each other, resulting from pressure. 
Microscopic examination shows that the granite 
consists of microline and orthoclase, plagio- 
clase, in very small amounts, quartz, biotite 
and muscovite, with occasional crystals of 
apatite and magnetite and rarely pyrite. 
Variations in the shade of the marketable 
granite, from very light to very dark gray, are 
due to the relative amounts of biotite which it 
contains. The rock is of medium grain and 
its constituent minerals are but slightly weath- 
ered. Pegmatitic offshoots, traceable directly 
to the granite mass were recorded by Mr. Fin- 
lay, and their dynamic effects on the enclosing 
schists were illustrated. The contact meta- 
morphism of the schist is inconsiderable. It 
is chiefly shown in the greater abundance of 
biotite and quartz in the immediate vicinity of 
the granite. Two dikes of augite-camptonite 
were found; one in the granite, the other 
in the country-rock. They are notable for 
the manner in which they have weathered. 
At times sixteen successive shells may be 
counted which are ready to break away from 
the main mass of the dike. Mention was also 
made, in discussing the glacial geology of the 
region, of sand plains and of two well devel- 
oped eskers. 
- The paper was discussed by Professors Kemp 
and Dodge and Drs. Julien and White. 
‘Note on a Sand Fulgurite from Poland,’ by 
SCLENCE. 
509 
A. A. Julien. Dr. Julien exhibited a speci- 
men of Fulgurite formed from sand, in Poland, 
with a series of micro-photographs which he 
had made from the same. Some new features 
in fulgurites were pointed out in this speci- 
men: pustules of glass on the inner lumen, 
glass-fibers on the exterior, and adhering sand- 
grains, two-thirds of which consist of ortho- 
clase. In the thin cross-section, examination 
of the minute gas-cavities showed the absence 
of condensed water-vapor, and this indicated a 
dilatation of both lumen and cavities by air, 
more than by steam. The radial arrangement 
of layer cavities, the hornlike projections on 
the exterior ofthe tube, and the pustules along 
the lumen were all shown to be connected 
with relief of intense pressure outwardly during 
the electric discharge, or inwardly during the 
reaction after its passage. This fulgurite is of 
further interestin presenting the first instance 
yet observed of devitrification, the glass being 
generally filled with delicate crystallites, ap- 
parently of feldspar. All the bubbles, how- 
ever, are enclosed in pellicles of homogeneous 
glass, and some of the larger within a coating 
of suddenly chilled glass, which is free from 
crystallites. The relation of these facts was 
discussed in reference to Lagorio’s view as to 
the difficult saturation of a magma by the con- 
stituents of feldspar. 
Other occurrences of fulgurites were dis- 
cussed by Drs. Kemp, Levison and White. 
THEODORE G. WHITE, 
Secretary. 
THE MINNESOTA ACADEMY OF NATURAL 
SCIENCES. 
THE February meeting of the Academy was 
addressed by Professor N. H. Winchell and Mr. 
Warren Upham on the following topics, respec- 
tively : ‘The Retreat of the Ice Margin Across 
Minnesota’ and ‘Giants’ Kettles in the Inter- 
state Park, Taylor’s Falls.’ 
Professor Winchell called attention to the 
general topography by means of a map of the 
State divided into three areas, viz.: Those 
areas above 1,400 feet, those between 1,400 and 
1,300 feet, and those below 1,300 feet, remark- 
ing that, as the ice must have slowly en- 
croached, in the form of glaciers, in the low- 
