40 UNIVERSITY OF MISSOURI STUDIES 



Winslow^ in 1894 called it the Moreau sandstone, while Ball and 

 Smith in 1903 called it the St. Elizabeth. Since Ulrich's report 

 in 1905, the name Roubidoux has been appUed to it. 



STRUCTURE 



The minor structural features of the area have been noted 

 under the descriptions of the formations and something as to 

 their general attitude was stated in discussing the physiography 

 (pages 9 and 10) but details of structure and its effects have not 

 been given. 



The structure of the formations is, on the whole, simple. 

 The rocks depart but slightly from a horizontal position over the 

 larger part of the region, except in two localities where they are 

 much disturbed. One of these, the Stony Point area, is in the 

 extreme southeastern corner of the area; the other, the Fertile 

 area, is at the junction of Mineral Fork and Big River. 



In general the beds dip gently to the north, northwest, and 

 west. The top of the Proctor dolomite at its highest outcrop 

 west of Hopewell is 1,080 feet, while its elevation on the west 

 side of the area on the North Fork, is about 1,000 feet, giving a 

 westward dip of about 1 1 feet to the mile. The same horizon on 

 Bates Creek has an elevation of about 1,020 feet, and on Mineral 

 Fork, about 10 miles farther north, about 950 feet, giving a dip 

 of 7 feet to the mile. On Little Indian Creek the elevation is 

 about 750 feet, showing a dip of 25 feet per mile for the last 

 eight miles. From near Fertile to Aptus there is a westward 

 dip of about 13 feet per mile. These average dips indicate some- 

 thing as to the larger features of the structure. Northeast of Lit- 

 tle Indian Creek the formations dip to the southwest more 

 steeply. 



Folding 



There are no marked or extensive areas of folding in the 

 region. Departures from horizontality may be divided into (a) 

 minor undulations and (b) major folds. 



(a) Minor undulations. — Most of the formations show mi- 

 nor warpings even in small outcrops. These are usually slight 



'Winslow, A., "Lead and Zinc Deposits," Mo. Geol. Sur., vol. 6, p. 

 331, 1894. 



