no. 2074. STUDIES ON FOSSIL FLORA— BERRY. 295 



what generalized sections will aid the reader in understanding the 

 relations. 1 



About one-eighth of a mile above Columbus the bluff is nearly 200 

 feet high and shows the following sequence of materials 



Feet. 



1. Loess apparently grading into the underlying member 50-60 



2. Yellowish to brownish ferruginous sand, often indurated, grading downward 



into a heavy gravel with some cobbles, often indurated to form great masses 

 of conglomerate, the lower one-third to one-half of the member conglomer- 

 atic the whole . . 40-50 



3. Gray sandy alluvial-looking laminated to massive siliceous leaf-bearing clay, 



toward the north in places a pink slightly sandy plastic clay about . . 80 



Southward a quarter of a mile and just north of the town the basal 

 portion of the bluff is made up of coarse angular somewhat silty, loose, 

 very crossbedded sand, carrying pellets and some laminae one to three 

 inches thick of grayish clay. These sands are prevailingly gray with 

 some ferruginous brown streaks and become finer and more argilla- 

 ceous upward. The clays appear at first silty and drab but bleach to 

 almost white and become indurated upon exposure and the leaf sub- 

 stance, represented by ulmic, humic or ferruginous materials, is leached 

 out, leaving only faint impressions. In places the leaves form matted 

 layers exactly comparable with those found in recent river deposits. 



At the Chalk Banks, 2 miles south of Columbus, the section is also 

 variable and has been much cut and slumped since the days of Owen 

 and Lesquereux. Following is a somewhat generalized section at the 

 latter locality: 



Feet. 



1. Loess more or less covered 60-80 



2. Compact ferruginous heavy gravel in a coarse sand 10-15 



3. Yellowish iron-stained slacked clay grading downward into next member 



about.. 10 



4. Gray clay with considerable fine white sand, generally thickly laminated and 



sparingly leaf bearing about. . 50 



At Hickman the bluff is about 185 feet above low water. The fol- 

 lowing section is somewhat generalized since there is considerable 

 lateral variation: 



Feet. 



1. Loess about. . 65 



2. Heavy gravel 10-15 



3. Gray siliceous micaceous leaf -bearing clay with calcareous concretions be- 



coming more sandy and softer toward the base about. . 105 



This lower 105 feet is obviously a formational unit, although Glenn 

 separates the softer basal 30 feet from the overlying 75 feet. The 

 clays are very unevenly laminated; where they are more sandy and 

 thinly laminated they contain more water, are darker in color, and 

 the leaf impressions are better preserved — where they are less sandy 

 and more massive, they are lighter in color, more indurated and the 



1 Aa previously mentioned, detailed soctions have been given by Owen and Loughridgo, but as the river 

 is cutting rapidly the exposures change from year to year. 



