308 



SCIENCE 



[N. S. Vol. LIV. No. 1396 



graded or renewed. On the contrary not only 

 was stream degradation repeatedly interrupted in 

 the glaciated area, but the surface there was re- 

 peatedly eroded glacially, and as many times re- 

 ceived glacial deposits. Thinking that these diff- 

 erences in Pleistocene history between the glaci- 

 ated and unglaciated parts of the continent might 

 have resulted in profiles notably discordant at or 

 near the drift border, a series of meridional topog- 

 raphic profiles was drawn from the Canadian bor- 

 der to the Gulf of Mexico. The results are nega- 

 tive in that no topographic break is shown at the 

 line separating the glaciated from the unglaciated 

 area, but on the whole the surface near the drift 

 border to the south is higher than that to the 

 north. The paper consists of a presentation of 

 these profiles and discussion of several possible 

 interpretations of their meaning. 



Intergladal volcanic ash: Chasles Ketes. 

 During the progress of extensive street grading in 

 the city of Des Moines, recently, there was dis- 

 closed immediately under the Wisconsin till sheet, 

 a white, claylike bed about a foot in thickness. 

 It manifestly did not belong with the drift or the 

 yellow loess beneath. Since the material was too 

 incoherent to be true clay, and was finely gritty, it 

 was examined under the microscope. It proved to 

 be typical volcanic ash, composed of transparent, 

 sharp-edged fragments of glass about one twentieth 

 of a millimeter in average size. The thick loess 

 deposit underneath is underlaid by the Kansan 

 till. This occurrence probably fixes, within very 

 narrow limits, the date of the volcanic outburst, 

 and the age of similar ash beds reported in Ne- 

 braska, Colorado and Wyoming. 



Erosion of high plateaux: Chaeles Keyes. 

 The lofty, flat-topped mountain ranges of eastern 

 Utah are usually treated as part of the great Cor- 

 dilleran uplift. Curiously, they now appear both 

 physiographically and tectonically to be wholly 

 unrelated. Although the repeated uplifting and 

 peneplanation which the Eockies have suffered are 

 appreciably reflected in the Utah field the amount 

 of erosion which the former has undergone enor- 

 mously surpasses that of the latter. Notwith- 

 standing the fact that both chains of mountains 

 are characterized by remnantal summital flats, the 

 latter seem to be nicely separated in point of 

 time. On the one hand thei summital plain of the 

 Eockies appears to be ancient Comanchan pene- 

 plain now being exhumed as the Dakotan sand- 

 stone is being stripped off. On the other hand the 

 terre pleins of the High Plateaux of Utah are re- 



ferred to the regional planation of Miocene times. 

 In the Cordilleran region these two horizons are 

 stratigraphicaJly separated by more than three 

 miles of sediments. The Jurassic-Comanchan pene- 

 plain of the Eockies is strongly reflected so far 

 east as Iowa and Minnesota; as is also the Mio- 

 cene peneplain of Utah. 



erasing of mountain massifs: Chakles Ketes. 

 The central massif of the Sierra de los Cucaras, 

 in Lower California, is a granitic type of rock not 

 very unlike that of the Sierra Nevada. Its nat- 

 urally blue-gray color darkens on exposure, thus 

 bringing out in strong contrast the wonderful vein- 

 ing, which is white. The veining in the vertical 

 walls of the mountain canyons has the appearance 

 of normal jointing set on edge, but on a colossal 

 scale, the cross-planes being filled with pegmatitie 

 materials to a thickness of two to six feet. To- 

 wards the north end of the mountain range the 

 titanic crazing is displayed in superb sections 1,500 

 feet high, in the famous Carriso Gorge, near the 

 United States boundary. 



Some Pleistocene sections at Des Moines : James 

 H. Lees. 



Some Carboniferous protozoa: Eula D. Mc- 



EWAN. 



The status of certain Synchonellid Brachiopods 

 from the Iowa Devonian: A. O. Thomas and M. 

 A. Stainbrook. The Synchonella alta Calvin from 

 the upper Devonian beds at Bird Hill, Hackberry 

 Grove, and elsewhere in Floyd and Cerro Gordo 

 counties, has been much confused in the literature 

 and in collections with a similar rhynchonellid shell 

 from the State Quarry beds near Solon. In most 

 cases in the Iowa reports the Solon species has 

 been called Bhynchonella pugnus or Pugnaa pugnus 

 (Martin). In some instances the two have been 

 entered under the same specific name and in others 

 the first has been made a varietal form of the sec- 

 ond. A study of their internal structures by Mr. 

 Stainbrook shows that each belongs to the genus 

 Pugnoides. They are specifically distinct. The 

 more robust but less acuminate State Quarry shell, 

 with a variable number of plications on its fold 

 and sinus, is made a new species, Pugnoides solon, 

 and the Lime Creek species becomes Pugnoides 

 altus (Calvin). Illustrations. 



A Ceplialopod from the Coal Measures at Mystic, 

 Iowa: A. O. Thomas. A fitne specimen of the 

 goniatite, Gastrioceras excelsum Meek, was recently 

 collected by Mr. Ben H. Wilson, a member of the 

 Academy. The specimen came from the Appa- 



