REVIEWS 407 



The surface of the ice is undulatory, conforming to the surface of the 

 underlying ground. In one place the slope is opposite to the movement 

 of the ice. The glacier as a whole may be traveling uphill for several 

 hundred feet, but the total rise of the upper surface is thought not to 

 exceed 20 feet. 



The glaciers are not notably advancing or retreating; in most places 

 cliff terminations at the shoreline indicate advance, but occasional 

 rounded "snout" endings bear witness to a slight retreat. The small 

 number of ice falls from the cliffs also disproves any notable advance. 

 In certain places the ice strata are slightly turned up at the glacier edges, 

 but there is no sudden upturning at the end; this conforms to the other 

 indications of but slight movement. 



Englacial material is rare and consists chiefly of wind- dropped rock; 

 sand, pebbles, and bowlders are uncommon. In one place the ice 

 grains were seen to be drawn out and arranged in sweeping curved lines 

 which follow the direction of glacial flow. The bounding crystal faces 

 are usually not plane but curved. 



From imperfect data collected on the speed of temperature waves 

 through the ice, it appears that a wave of about 5 change in temperature 

 penetrates 2 feet in about 2 days, and 4 feet in about 5 days. 



The islands seem to be the serrated tops of a mountain range which 

 has been deeply dissected by glaciers while the islands stood at a mark- 

 edly higher elevation above the sea. 



T. T. Q. 



The Upper Devonian Delta of the Appalachian Geosyncline. By 

 Joseph Barrell. In three parts. Am. Jour. Sci. [4th Ser.j, 

 X^XXVI (November, 1913), 429-72; XXXVII (January, 

 1914), 87-109; XXXVII (March, 1914), 225-53, Figs. 5- 

 The Upper Devonian Oneonta and Catskill formations, that consist 

 of alternating red shales and gray sandstones, of the Appalachian geosyn- 

 cline in southeastern New York and northeastern Pennyslvania are 

 believed to be "subaerial delta deposits [of westward-flowing streams] 

 in a dry but not arid climate; a climate probably equable in temperature 

 but subject to seasonal rainfall." The Oneonta is 1,000 feet thick in 

 the Catskill Mountains; the Catskill runs up into thousands of feet in 

 thickness. The Portage and Chemung formations are the shallow-sea 

 equivalents of the Oneonta and Catskill beds. The inland sea in which 

 the former were deposited bordered the subaerial delta on the west and 

 southwest. The included map "shows the shore line at the close of the 



