506 abstracts: technology 



The rocks next younger are massive limestones carrying Triassic 

 fossils. In the Nutzotin Mountains there are banded slates and gray- 

 wackes, scantily fossiliferous, which may be in part Triassic. 



Shales and graywackes of Jurassic age have been recognized in the 

 region, but their upper and lower limits were not determined. Shales 

 and graywackes, carrying Lower Cretaceous fossils, lie immediately 

 above the Jurassic beds, without any observed stratigraphic break. 



Tertiary sediments are represented by small, detached areas of shale, 

 sandstone, conglomerate, and tuff, with minor amounts of lignite. Cer- 

 tain old but unconsolidated gravels are also probably of Tertiary age. 

 The extrusion of widespread lava flows was also begun in Tertiary time 

 and has continued intermittently ever since, so that it is difficult to 

 separate the Tertiary from the Quaternary lavas. 



Quaternary deposits are present in considerable variety and abun- 

 dance. The oldest consist of glacial till and outwash gravels interbedded 

 with lava flows, representing a stage of glaciation much earlier than the 

 last notable ice advance. These older glacial deposits are overlain by 

 extensive lava flows. During their last great advance the glaciers left 

 deposits of morainal material scattered throughout the district. Large 

 deposits of outwash gravels were laid down during the retreat of the 

 ice and are still accumulating in the valleys of the glacier-fed streams. 

 Accumulations of talus, peat, and muck, with some volcanic ash, and 

 the products of normal stream deposition make up the postglacial 

 materials in the areas not now receiving glacial and glacio-fluvial 

 deposits. A. H. B. 



TECHNOLOGY. — The properties of some European plastic fire clays. 

 A. V. Bleininger and H. G. Schurecht. Bureau of Standards 

 Technologic Paper No. 79. Pp. 34. 1916. 



The properties of five well known European plastic fire clays, largely 

 used for glass pots, graphite crucibles, etc., have been studied for the 

 purpose of securing data, making possible a comparison with similar 

 American clays. Such properties as the content of shrinkage and 

 pore water, drying shrinkage, fineness of grain, rate of drying, mechani- 

 cal strength in the dry state, rate of vitrification, final softening tem- 

 perature, and the chemical composition were determined. 



From the results obtained it was shown that these famous European 

 clays do not differ radically from similar materials found in this country 

 but that the same, or possibly superior, results can be obtained with 

 mixtures of known American clays. A. V. B. 



