974 



SCIENCE 



[N. S. Vol. XXX. No. 783 



striking examples of solution cavities and caverns 

 occur in the flanks of the Ozark uplift in Missouri. 

 Some of the caverns are excavated in the pre- 

 Ordovician Jefferson City dolomite, others in 

 Niagara limestone; the filling in either case con- 

 sisting chiefly of late Devonian and early Missis- 

 sippian sandstones. Others again occur in late 

 Devonian limestone, while several instances in 

 Ordovician limestone of Lowville and Stones River 

 age were found filled with later Ordovician sedi- 

 ments. Philip S. Smith, 



Secretary 



The 223d meeting of the society was held at 

 the George Washington University on Wednesday 

 ■evening, November 24, 1909. 



Regular Program 

 Roch Glaciers in Alaska: Stephen R. Capps. 



The rock glaciers, a hitherto undescribed fea- 

 ture, occur in large numbers and in exceptionally 

 perfect development in the area covered by the 

 Nizina Special Map, Copper River region, Alaska. 

 They all head in glacial cirques and extend from 

 these down into the valleys, varying in width from 

 one tenth to three fifths miles, and in length from 

 one half to two and one half miles. The surface 

 slopes range from 9° to 18°. In slopes, shape and 

 surface markings they bear a striking resemblance 

 to glaciers. In the upper portions longitudinal 

 ridges and furrows are conspicuous, while toward 

 the lower ends the ridges become concentric, par- 

 allel with the borders of the lower ends of the 

 flows. A few of the rock glaciers actually grade 

 into true glaciers at their upper ends. Most of 

 them, however, show no ice or snow on the sur- 

 face, the fragmentary rook of which they are 

 ■composed extending up to the cirque walls above. 



All the rock glaciers examined were found to 

 be cemented with interstitial ice, which filled the 

 openings to within a few feet of the surface at 

 their upper ends, but was farther from the surface 

 in the lower ends. This ice has imparted to the 

 mass of'trock waste a kind of glacial movement 

 which is thought to be still in operation in many 

 of the flows. The typical rook glaciers differ from 

 true glaciers in that they head in cirques in which 

 there are no perennial snows; in the purely in- 

 terstitial character of the ice; and in their ability 

 to endure in climatic conditions in which ordinary 

 glaciers can not exist. 

 Canyon de Chelly, Arizona: M. R. Campbell. 



(No abstract.) 



Geological Observations in Iceland: Feed. Eugene 



Weight. 



Geologic mapping in Iceland is still in the 

 reconnaisance stage. Most of its geologic features 

 are as yet known only in a general way. Like the 

 Faroe Islands, Iceland consists almost wholly of 

 volcanic rocks (basalt) and associated tuffs and 

 breccias. Thorrodsen has shown that the earliest 

 rooks now exposed are probably of early Miocene 

 age and that volcanic activity has characterized 

 the island since its uplift in early Miocene or late 

 Eocene. Among its most striking structural fea- 

 tures is block faulting, but interest in the island 

 centers chiefly in its volcanic and glacial phe- 

 nomena. Among the former are explosion craters, 

 lava cone craters, crater series along faults, fissure 

 eruptions, secondary craters, etc., in model-like 

 development and on a scale far surpassing that of 

 any other country. Among the latter are the 

 erosional effects of both continental and valley 

 glaciers, especially prominent in north Iceland 

 where the basalt formation is nearly flat-lying 

 and homogeneous in character. The valleys ex- 

 hibit: U-oross-sectiOns, hanging side valleys, 

 steepening of grade toward valley head with tend- 

 ency toward cirque development, glacial grooves 

 and markings along valley sides, truncation and 

 alignment of spurs, etc., between tributary valleys, 

 low cigar-shaped spurs at junction of larger tribu- 

 tary valleys attenuated by overriding of glaciers 

 confluent at acute angles. In a country covered 

 with an ice-cap, the surface of the ice sheet is an 

 important plane of reference which in its physio- 

 graphic effect is often similar to that of a water 

 surface, as sea-level, toward which all exposed land 

 surface tends to be reduced. The mountains and 

 rock cliffs emergent above the ice-sheet undergo 

 rapid changes in temperature with accompanying 

 shattering due to expansion of included moisture 

 in freezing, and tend to break down rapidly and to 

 be reduced to the level of the ice surface. What- 

 ever the nature of the erosional activities going on 

 below the surface of the ice cap, the ultimate 

 result will be a truncation of the mountains at 

 a common level, strongly resembling in appear- 

 ance an uplifted and dissected peneplain. 



Feancois E. Matthes, 



Secretary 



At the 224th meeting of the society, held on 

 December 8, 1909, Mr. Arthur Keith presented 

 the following paper : " The Status of Geologic 

 Names." 



The student of stratigraphy in anything except 



