792 



SCIENCE. 



[N. S. Vol. XVII. No. 437. 



are blown about by the wind, remain dormant 

 under the snow through the long winter sea- 

 son, and, if the proper conditions are present, 

 take root in the soil the following spring. 

 The mechanical structure of the shoots which 

 enables the plant thus to disseminate and to 

 perpetuate the species was described and il- 

 lustrated by specimens and by photographs. 

 F. A. Lucas. 



THE GEOLOGICAL SOCIETY OF WASHINGTON. 



At the 142d meeting of the society, held 

 in the assembly hall of the Cosmos Club, 

 Wednesday evening, April 8, 1903, the fol- 

 lowing program was presented: 



Mr. J. E. Spurr, 'The Eelation of Faults 

 to Topography.' , 



Folds and faults are closely associated gen- 

 etically, and their effect on the surface relief 

 is analogous. Each may be divided into three 

 orders : 



1. Those affecting great areas, as portions 

 of continents. 



2. Those affecting broad belts, producing 

 mountain systems. 



3. Folds and faults proper, being wrinkles 

 and fractures on the grander flexures and dis- 

 placements of the first and second orders. 



Gravity antagonizes these disturbances, in 

 so far as they affect surface relief. On ac- 

 count of the relative bulk of material to be 

 readjusted, and for other reasons, erosion is 

 generally ineffective in combating flexures and 

 dislocations of the first and second orders, 

 while folds and faults proper are generally 

 overconje. So the anticlinal ridge and the 

 S3mclinal valley of direct deformation are 

 relatively rare as compared with the anticlinal 

 ridge, the synclinal ridge and the anticlinal 

 valley of erosion. Similarly, the speaker's 

 studies have convinced him that the analogous 

 features of relief connected, with faults have 

 about the same proportion. Simple fault- 

 scarps (analogous to ridges and valleys of di- 

 rect deformation) are relatively rare; while 

 normal erosion fault scarps and reversed ero- 

 sion fault scarps (analogous to anticlinal and 

 synclinal ridges of erosion) are about equally 

 abundant. The foi'ms indirectly expressed on 



the topography by the erosion of folded and 

 faulted rocks also differ in different climates. 



Mr. Waldemar Lindgren, ' Metallic Sul- 

 phides from Steamboat Springs, Nevada.' 



During a visit to Steamboat Springs in 

 1901, it was found that a shaft forty feet deep 

 had been sunk through the sinter deposits near 

 the railroad station. Below the sinter, 'a 

 gravel of well-rounded granitic and andesitic 

 pebbles was found, and in this gravel, which 

 is probably an older deposit of Steamboat 

 Creek, minute needles of well-crystallized 

 stibnite were found to be very abundant. 

 The gravel also contains well-crystallized 

 pyrite, and some opal often coats the surface 

 of the pebbles. From the investigations of 

 Dr. Becker it is known that the sinters con- 

 tain sulphides of arsenic and antimony, but 

 no well defined or crystallized minerals cor- 

 responding to these salts have previously been 

 found. Since the gravels in which the crystal- 

 lized stibnite and pyrite occur seem to be free 

 from the sulphide of arsenic which is found 

 in the overlying sinters, it is inferred that the 

 conditions of deposition in the two eases are 

 different. 



Mr. Geo. I. Adams, ' Origin of Bedded 

 Breccias in Northern Arkansas.' 



The fracturing and brecciation in the 

 northern Arkansas zinc and lead district are 

 probably due to stresses induced at the time 

 of the folding in the Ouachita Mountain and 

 Arkansas valley regions. At the close of 

 the Carboniferous period the thick mass of 

 sediments which had accumulated in what is 

 now central Arkansas and western Indian 

 Territory was deformed in a manner which 

 suggests that the beds were thrust to the 

 northward. In the Ouachita Mountains there 

 are close folds and thrust faults; in the Ar- 

 kansas valley region, open folds. In the 

 southern border of the Ozark region, and 

 particularly in the zinc and lead district of 

 northern Arkansas, the generally horizontal 

 position of the rocks was retained, but there 

 was considerable movement of individual 

 beds, especially in the Ordovician series. The 

 variation in the structure of the Ordovician 

 dolomites, which are in places massively bed- 

 ded and in other places thin-bedded, lamin- 



