634 



SCIENCE 



[N. S. Vol. XXIX. No. 746 



chemical composition of each of these ores, the 

 localities in which the deposits occur, and also 

 their geologic and stratigraphic relations. 



After this was presented: 

 The Shortage of Coal in the Northern Appalachian 



Field: I. C. White, Morgantown, W. Va. 



The next paper was read by title : 

 Glacial Character of the Yosemite Valley: Fkan- 



gois Matthes, Baltimore, Md. (Introduced by 



Wm. Bullock Clark.) 



Then was presented: 

 The Mills Moraine mth some discussion of the 



Glacial Drainage of the Longs Peak {Colorado) 



District: Edwasd Obton, Jr., Columbus, Ohio. 



(Introduced by F. P. Gulliver.) 



This paper was discussed by Mr. W. T. Lee. 



The next paper read was: 

 Quartz as a Geologic Thermometer: Feed E. 



Weight and E. S. Laesen, Washington, D. C. 



Observations by Le Chatelier and Mallard in 

 1889-1890 proved that at about 570° quartz crys- 

 tals undergo a reversible change, the expansion- 

 coefficient, birefringence and circular polarization 

 all changing abruptly. 0. Miigge {Neues Jahr- 

 huch, Festiand, 1907, 181-196) has recently con- 

 sidered the problem again in detail and by means 

 of etch figures combined with crystallographic 

 behavior on heating found that below the inver- 

 sion point quartz crystallizes in the trapezohedral- 

 tetartohedral division of the hexagonal system, 

 while above 670° it is trapezohedral-hemihedral. 

 The high form is very similar to the low form 

 and differs chiefly in the fact of its common planes 

 of symmetry. A plate formed above 570° is trape- 

 zohedral-hemihedral, but on cooling it changes to 

 the trapezohedral tetartohedral division, thereby 

 losing its common planes of symmetry, which may 

 then become twinning planes. It is to be expected, 

 therefore, that quartz crystals thus cooled will be 

 irregularly and intricately twinned after (1010.), 

 while low temperature quartzes are simple or 

 regularly twinned. It is furthermore evident, on 

 considering the genesis of quartz at different tem- 

 peratures, that intergrowths of right- and left- 

 handed quartz are limited chiefly to quartz crys- 

 tals formed below 570°. These two criteria can 

 be used to distinguish quartz which has been 

 formed or heated above 570° from quartz which, 

 has never reached that temperature. The object 

 of the present investigation has been to test the 

 general validity of the theoretical conclusions on 

 a number of quartzes from different kinds of 

 rocks and veins, as well as to determine more 

 accurately the inversion temperature. 



SECTIONAL meeting FOB PAPEES ON STEATIGBAPHIC, 

 AKEAL AND PALEONTOLOGIC GEOLOGY 



The section was called to order at 10 o'clock 

 Thursday morning by Professor W. B. Clark, who 

 was then elected presiding officer. Professor E. 

 R. Cumings acted as secretary throughout, by 

 request of the secretary of the society. 



The first paper read was: 



Occurrence of the Magothy Formation on the 



Atlantic Islands: Aethuk Barneveld Bibbins, 



Baltimore, Md. 



The Magothy formation (of mid-Cretaceous 

 age), as originally defined by Darton, was sup- 

 posed by that author to be limited to the state 

 of Maryland, although its partial equivalent, the 

 " alternate clay-sands," was earlier mentioned by 

 Uhler as occurring much farther northward. Re- 

 cent investigations, paleobotanical and strati- 

 graphic, by Hollick, Berry and the writer have 

 extended the lines of the formation far southward, 

 and northward across New Jersey and along the 

 Atlantic Islands as far as Marthas Vineyard. 

 The occurrence upon these islands was shown by 

 local sections and photographs. The deposits are 

 richly plant bearing, with grains of amber asso- 

 ciated, as on the Magothy River. The formation 

 suffered considerable corrugation by the great ice 

 sheet. 



The paper was discussed by Dr. David White 

 and Professor A. B. Bibbins. 



The next paper presented was: 



Erosion Intervals in the Tertiary of North Caro- 

 lina atid Virginia and their hearing upon the 

 Distriiution of the Formations: Benjamin L. 

 MiLLEE, South Bethlehem. 



Recent investigations have furnished evidence of 

 several uplifts and subsidences during Tertiary 

 time in North Carolina and Virginia that have 

 determined the present distribution of the forma- 

 tions. These have affected large areas at certain 

 periods but at other times have been localized. 



Then followed: 

 The Character and Structural Relations of the 

 Limestones of the Piedmont im Maryland and 

 Virginia: Edwabd B. Mathews and J. S. 

 Geasty, Baltimore, Md., and Charlottesville, Va. 

 A study of the small bodies of crystalline lime- 

 stones and marbles found along the western edge 

 of the Piedmont from Pennsylvania to North 

 Carolina shows that their occurrences mark the 

 tops of tightly compressed anticlines. The de- 

 posits on either side are usually metamorphosed 

 volcanics — flows and tuffs — which in the normal 



