May 17, 1907] 



SCIENCE 



769 



tion and are closely associated with crater 

 cones of the ordinary type. 



The geology of the surrounding regiflns 

 indicates that the craters may be underlain 

 by beds of salt, gypsum and limestone, the 

 removal of which, by solution, may in part 

 account for the depressions. The crater 

 rims, however, composed of the material of 

 the plain commingled with volcanic cinders, 

 yield unmistakable evidences of explosive 

 action, from which the inference is drawn 

 that the craters are probably best explained 

 as due to explosions of steam or other vol- 

 canic gases. 



Volcanic Nechs of the Mt. Taylor Region, 

 New Mexico: D. W. Johnson. (Intro- 

 duced by AV. M. Davis.) 

 Some doubt has been expressed as to the 

 correctness of interpreting as volcanic 

 necks certain buttes which show vertical 

 columnar structure, and which are sur- 

 rounded at lower levels by undisturbed 

 sedimentary beds. The Devil's Tower, of 

 Wyoming, has been referred to a laccolithic 

 origin, in part at least, because it shows the 

 features mentioned, and the interpretation 

 of buttes of the Mt. Taylor region as necks 

 has been questioned. The paper presents 

 evidence to show that the buttes of the Mt. 

 Taylor region are undoubted volcanic 

 necks, surrounded by undisturbed sedi- 

 ments, and exhibiting vertical columnar 

 structure in many cases. The general his- 

 tory of the vulcanism and erosion of the 

 region is considered, and the structural 

 details of the neck discussed. 



Earth-flows at the Time of the San Fran- 

 cisco Earthquake: Robekt Anderson. 

 (Introduced by Ralph Arnold.) 

 This paper treats of a variety of land- 

 slides caused by the concentration of water 

 at certain points near the surface of gentle 

 or steep slopes. Earth-flows are defined as 

 slides or flows of portions of the surface of 



slopes where the surface material has been 

 saturated, loosened and weighted down and 

 caused to cave away and flow or creep as a 

 semi-fluid mass. They are distinguished 

 from avalanches or comparatively dry land- 

 slides of otherwise loosened material. A 

 number of instances are described and em- 

 phasis is given to their importance as initial 

 factors in the formation of drainage lines. 



Badio-activity of the Thermal Waters of 

 Yellowstone National Park: Herman 

 ScHLUNDT and Richard B. Mooee. (In- 

 troduced by C. W. Hayes.) No abstract 

 received. 



A Lower Huronian Ice Age: A. P. Cole- 

 man. 



Since the final proof of the Permian 

 glacial period of India, Australia and 

 South Africa, more attention is being paid 

 to the evidences of still more ancient glacia- 

 tions, e. g., in Cambrian times. For years 

 the writer has believed that the 'slate con- 

 glomerate' at the base of the Lower Hu- 

 ronian of Canada is glacial, since it con- 

 tains angular and subangular boulders of 

 all sizes up to cubic yards, enclosed in an 

 unstratified matrix. These -boulders are 

 often miles from any possible source. Re- 

 cently, striated stones have been broken out 

 of their matrix in the Lower Huronian of 

 the Cobalt silver region, giving still 

 stronger proofs that the formation is an 

 ancient boulder clay. The results of this 

 investigation have an important bearing on 

 the earth's early history, since the Lower 

 Huronian has only one known formation 

 before it, the Keewatin. The earth's in- 

 ternal heat was not sufficient at that time 

 to prevent the formation of an ice sheet in 

 latitude 46 degrees. 



Professor Coleman's paper was discussed 

 by Professors Miller, Salisbury, Lane, Bell 

 and Clapp. 



