OQ GEOLOGICAL RECONNOISSANCE 



The section of the quaternary beds at the Chalk Bluffs, as far as they 

 can be seen, is as follows: 



Hyht Thich 



above flm . 



river. v-*-v-«^ 



135. Hill on which the ferryman's house stands 



Soil and sub-soil 



Chert and hornstone gravel 25 



110. Lowest point to which the upper gravel bed could be traced. 



105. Top of the first bench below the main gravel bed 



Pink and variegated sand; locally indurated into a soft 



crumbling sandstone 96 feet or more in thickness 9G 



30. White siliceous clay shale or marly earth, slightly indurated 



at the upper part 



6. Fine white potter's clay 5 to G feet 6 



0. Low water of the St. Francis river. 

 The materials which compose the gravel bed which underlies the sub- 

 soil seem to have been derived from the destruction of beds of carbon- 

 iferous date, lying to the north in the State of Missouri. At this locality, 

 it appears to be from 25 to 30 feet in thickness. It occupies the highest 

 position of the beds of quarternary date at this locality. 



No solid beds of rock have been observed in this north-east termination 

 of Crowley's ridge. In sinking wells at levels below the gravel bed, they 

 pass through sand, then streaks of clay and shaly materials, below which 

 the sand continues. In this lower bed of sand the water is usually struck, 

 which must be retained there by the lower beds of clay of the preceding 

 section. Sometimes, in low situations, they pass through beds of clay in 



digging for water. 



A few chert and hornstone pebbles were observed disseminated amongst 

 the sand at 40 feet above the river, but the principal gravel deposit of 

 this part of Crowley's ridge is in high situations above the great mass of 



sand. 



The growth on the high ground is mostly black and white oak; in the 

 bottoms, a mixed growth. Considerable groves of cypress timber nourish 

 in the bottoms of St. Francis river, a short distance above Chalk Bluffs. 



An erratic mass of hornstone, weighing upwards of 50 pounds, was 

 observed on the slope of the river bluff, near the ferry; and near by are 

 chalybeate oozings from the bank, originating, probably, from some scaly 

 oxide of iron, sparingly disseminated in the adjacent bank. 



The potter's clay at the base of the Chalk Bluffs is nearly white, or of a 

 cream color; variegated, however, here and there, with flesh tints. Its 



