FEBRUARY 23, 1912] : 
material. Thus far no success has attended these 
efforts, but with persistent frequency hopes are 
aroused over some new ‘‘find’’ and glowing an- 
nouncements are made of the possibilities of this 
industry. The onyx found is of cave formation 
and for the most part represents the remnants of 
vanished caves. The character and extent of the 
deposits was discussed and the possibilities of 
their commercial development. 
Variation of the Optic Angle of Gypsum with 
- Temperature: Epvwarp H. Kraus. 
By using an oil bath to determine the variation 
of the angle of the optic axes of gypsum at dif- 
ferent temperatures it is found that gypsum is 
optically uniaxial at approximately 90° C. for 
sodium light. Although Mitscherlich observed in 
1826 that this change takes place at about 92°, 
the values given later by Des Cloizeaux, and more 
recently by Tutton, both of whom used air baths, 
are from 15° to 26° too high. Neverthless, Des 
Cloizeaux’s value of 116° C. for red light is the 
one commonly quoted. By plotting the values of 
the apparent angles of the optic axes at various 
temperatures up to 132.5° C., it is easily seen that 
the angle changes most rapidly in the vicinity of 
the uniaxial point, that is, between 80° and 100°, 
and further, that one axis, as was pointed out by 
Naumann, changes its position more rapidly than 
the other. 
Notes on the Paragenesis of the Zeolites: J. VOu- 
NEY LEwIs. 
Zeolites and other secondary minerals occur in 
the Newark igneous rocks of New Jersey: (1) in 
cavernous spaces in the ropy pahoehoe of the ex- 
trusive Watchung basalts; (2) in fault fissures 
and fault-breccia of both the basalts and the great 
intrusive sill (Palisades, Rocky Hill and Sourland 
Mountain); (3) less commonly in the ordinary 
joint cracks of both the extrusive and the intrusive 
types. The rocks are essentially the same in both 
chemical and mineral composition, consisting essen- 
tially of pyroxene and plagioclase feldspars, with 
quartz-bearing and olivine-bearing facies. The 
zeolites and related silicates are essentially com- 
binations of the feldspathic elements and water, 
with the addition of fluorine in apophyllite and 
boron in datolite; the accompanying amphibole, 
biotite, chlorite, epidote, serpentine and tale are 
derivatives of the pyroxenes. Hypotheses of origin 
dependent on the action of meteoric waters are 
inapplicable on account of difficulties of circula- 
tion, deoxygenation and sources of fluorine and 
boron; on the other hand, contact metamorphism 
SCIENCE 
313 
by the intrusives has produced in the adjacent 
shales minerals into which fluorine and boron enter, 
presumably by emanation from the magma. Hence 
magmatie waters are regarded as the most prob- 
able agent in the*formation of the zeolites and 
accompanying minerals. 
The paper was discussed by A. C. Lane and 
F. R. Van Horn. 
Peculiar Iron Ore from the Dunham Mine, Penn- 
sylvania: W. S. BAYLEY. 
No abstract received. 
Glacial Deposits of the Continental Type wi 
Alaska: R. 8. TarrR and LAWRENCE MaRrrTIN. 
The glaciation of the interior of Alaska forms 
a striking contrast with the coast, where glacial 
erosion forms predominate, the deposits being 
largely under water, except for (1) 1,600 square 
miles east of Yakutat Bay, (2) 16,000 square 
miles in the Cook Inlet-Susitna Valley region, and 
smaller areas. The interior, between the coast 
ranges and the Endicott-Rocky Mountain system, 
where the National Geographic Society’s party 
made some studies in 1911, has extensive glacial 
deposits of the continental type, previously de- 
scribed in part by Russell, Brooks and others and 
similar to those of the United States. These in- 
clude at least (a) 15,000 square miles in the Cop- 
per River basin, (b) 27,000 square miles in the 
Tanana and Kuskokwim valleys, (c) 17,000 square 
miles in the Yukon Flats, (d) several thousand 
square miles on the Upper Yukon region in Canada 
and smaller areas. The dominant material is out- 
wash and this extends long distances outside the 
country actually glaciated. In places there is 
wind-blown loess associated with this. In some 
localities it is still being deposited, and in the 
Copper River basin it has been accumulating dur- 
ing the time required for the growth of six or seven 
generations of trees. There is also some till, but 
this is largely buried beneath outwash. Lake 
deposits, eskers, kames and buried vegetation are 
also found, but thus far no one has found drum- 
lins. In thickness, some of these deposits rival 
those of the middle west, one instance being known 
of probably 800 feet of gravel, sand, ete., grading 
out from the mountains to less than 100 feet fifty 
miles away. The presence or absence of these 
drift deposits seems to be chiefly a matter of 
favorable topography and existing deglaciation, a 
process much like that formerly in progress in 
northeastern and central United States. 
The paper was discussed by W. M. Davis, C. A. 
Davis and H. M. Eakin. 
