98 THE JOURNAL OF GEOLOGY. 



terraces 130, 150, or even 180 feet above tide -water. These clays are the 

 result of a late glacial or postglacial submergence of the valley, but their 

 upper surface does not indicate the amount of their submergence, as they 

 are bottom deposits. Delta deposits made by the tributary streams, where 

 they entered the Hudson estuary, would indicate the amount of submergence. 



Such deposits are found on the Catskill a mile north of Cairo, and eroded 

 remnants are traceable for three or four miles down stream. The surface is 

 characterized by great numbers of water -worn stones up to fifteen or eight- 

 een inches in diameter. The lobate margin, where present, is poorly 

 defined. These deposits range from 290 feet (aneroid) above tide, up 

 river, to 270 feet further cown. One -tenth of a cubic mile of material seems 

 to have been washed into the Catskill trench at the point of this delta between 

 the time of the ice departure and the elevation of the land. Subsequent ter- 

 racing has removed half that amount. 



The course of the Catskill at Leeds, where it crosses a ledge of hard 

 Corniferous limestone is probably of postglacial superimposed origin, but 

 the preglacial valley cannot be definitely fixed. H. B. K. 



Geological Survey of Alabama. — Bulletin 4. By C. Willard Hayes. 

 (Report of the Geology of Northeastern Alabama and Adjacent 

 Portions of Georgia and Tennessee). 



This report covers an area of 5950 miles, two -thirds in Alabama. Topo- 

 graphically it falls into three divisions: i) the Cumberland and other 

 plateaus of the northwest; 2) in the center, anticlinal valleys — Browns and 

 Wills, with the synclinal mountains — Sand and Lookout; 3) the monoclinal 

 mountains, the " flatwoods " (Coosa shales) and the chert hills (Knox lime- 

 stone) of the southeast. The drainage of the first is radial from the center 

 of the plateau to the Tennessee ; that of the second, once consequent upon 

 the folded structure, is now adjusted to the strike of the soft beds. 



The formations are Cambrian, Silurian, Devonian and Carboniferous. 

 Total thickness is from 13,000 to 18,000 feet in the east, but decreases west- 

 ward. Hard sandstones of the Carboniferous form the cappings of the 

 plateaus and synclinal mountains. In the anticlinal and monoclinal valleys 

 the Silurian and Cambrian appear. The rocks pass from the nearly hori- 

 zontal beds of the plateau region, by narrow unsymmetrical anticlines with 

 steeper dip on the northwest side, and by broad shallow synclines, to the 

 complicated folds of the southeast. The axes of these latter folds dip more 

 or less abruptly northward and southward, causing the ridges to assume 

 zigzag courses. Synclines are often crossed by anticlines. 



Thrust faults exist, some of great magnitude, and traceable for 200 to 300 

 miles. By the " Rome thrust fault " the Cambrian shales have been shoved 

 four to five miles over upon the Carboniferous shales. Most of the over- 



