492 



SCIENCE 



[N. S. Vol. XLTII. No. 1220 



THE AMERICAN ASSOCIATION FOR 



THE ADVANCEMENT OF 



SCIENCE 



SECTION E— GEOLOGY AND GEOGRAPHY. II 



Preliminary report on experiments relating to con- 

 tinental deformation: E. T. Chamberlin and 



J. T. ElCHAKDS. 



The previous paper dealt witli faulting, whicli 

 may be regarded as a local, superficial phenomenon 

 of continental masses; the present paper relates to 

 the deformation of these greater masses. To at- 

 tack this greater problem it seemed desirable to de- 

 vise a mode of compressing blocks that have the 

 shape of a continental sector of the earth with 

 radial sides and superficial curvature. A machine 

 for such sector crushing was built with movable 

 steel jaws hinged below and corresponding in posi- 

 tion to radii of the sphere. Into this a triangular 

 wedge-like mass was molded with a surface curva- 

 ture similar to that of a continent. By the use of 

 a powerful jack, this representative of a conti- 

 nental sector could be squeezed by varying pres- 

 sures reaching up to many hundreds of pounds per 

 square inch. For experiments upon materials of 

 uniform strength, pure paraffine was used; for ex- 

 periments embodying the principle of increasing 

 strength of materials with increasing depth below 

 the surface in accordance with Dr. Adams's de- 

 ductions from his experimental researches, there 

 were molded, one above another in a series of 

 zones of predetermined resistance, mixtures of 

 plaster and parafSne in definite proportions. In 

 all these experiments the prevalent type of fault- 

 ing was that of a triangular wedge. This partic- 

 ular shape appears to be very significant, as has 

 been suggested before. This wedge faulting nat- 

 urally enough appeared first in the surficial por- 

 tion of the sector; later after some relief had been 

 realized above, and movement below had become 

 less restrained, additional fracturing set in below. 

 "When parafSne alone was used, the numerous rough 

 spots of the enclosing steel side-plates made trail- 

 ing scratches on the soft material. These scratches 

 served as autographic records of the different di- 

 rections of internal movement of the material in 

 reshaping itself into the separate wedges which 

 came to divide the sector. As the scratches in 

 many cases curved sharply, they indicated not 

 only the various directions of movement of the 

 separate portions of the sector, but also the order 

 of succession of the individual movements that en- 

 tered into the formation of each block. Further 

 experimentation along these lines seems likely to 

 throw some light upon the in/ternal adjustments of 



masses within the earth while undergoing dias- 

 trophism. 



Origin of the stylolitic structure in Tennessee 



marble: C. H. Gordon. 



The marble known commercially as the Tennessee 

 marble comes from what is known as the Holston 

 formation, which is of Ordovieian age. The pro- 

 ducing areas occur chiefly in the central portions 

 of the East Tennessee Valley region with Knox- 

 vUle as a center. The marbles are sub-crystalline 

 to more or less completely crystalline in texture 

 and vary in color from light pink and gray to dif- 

 fering shades of red, dark chocolate and cedar. 

 At the present time the light pink and gray are 

 the leading varieties. One of the striking features 

 of these marbles is the presence of thin, dark-col- 

 ored interlocking seams or sutures known tech- 

 nically as stylolites. In the main these extend 

 approximately parallel with the bedding or grain 

 of the stone but not infrequently they are more or 

 less inclined to this and at times cut the rock in 

 all directions. The theories proposed to account for 

 stylolitic structure are briefly considered and the 

 solution theory accepted as being the most satis- 

 factory. The chief question involved is as to 

 whether these represent actual parting planes as 

 heretofore usually considered, or fractures. It is 

 the conclusion of the writer that while many of the 

 sutures, especially in the more impure portions of 

 the formation are undoubtedly parting planes, 

 those in the massive light-colored stone have been 

 formed along fractures instead of bedding planes. 

 From the high content of carbonate of lime 

 (98J-99 per cent.), the rich profusion of organic 

 remains, chiefly bryozoa and crinoids, the irregu- 

 larity in development, and certain features indi- 

 cative of disturbed conditions in sedimentation, it 

 is suggested that accumulation of the deposits 

 took place in clear but shallow waters on reefs or 

 banks where colonies of the types represented es- 

 tablished themselves and grew in rich profusion. 

 If reefs were present they were bryozoa reefs and 

 not coral reefs, as no undoubted corals have been 

 observed in the formation. 



Seport on the discovery of ancient glaciation on 

 Mauna Kea, Hawaii: Wm. Alansen Bryan. 

 Eeporting the discovery in July, 1916, of an an- 

 cient mountain glacial field fifty square miles in 

 extent on the summit of Mauna Kea (13,825 feet), 

 the highest mountain in the Pacific Ocean, to- 

 gether with an account of a subsequent ascent of 

 Mauna Kea, Hualalei, and Mauna Loa for the pur- 

 pose of securing comparative data for the determi- 

 nation of the relative age of these three important 

 subtropical mountain summits. 



