.1 



The Occurrence of Conglomerate and Sandstone of Post- 

 glacial Origin in Jefferson County, Indiana. 



By Glenn Cllbertson. 



The city of Madison, Jefferson County, Indiana, lias been built on a 

 great sand and gravel bar. This bar is approximately three miles long, 

 from a quarter to a half mile wide, and of varying depth up to sixty or 

 eightj' feet. It is composed quite largely of sand, gra^-el and pebbles of 

 glacial origin, water worn and deposited by the Ohio river. The bar de- 

 posit was very probably formed contemporaneously with tiie "second bot- 

 toms" or the first terrace of the Ohio river, and during the time of flooded 

 waters as the later glaciers were melting. 



Crooked creek, a stream some eight or ten miles long, which in glacial 

 or preglacial times emptied into the Oliio near what is now the upper part 

 of the city was deflected by these deposits, and now flows approximately 

 parallel to the Ohio river for some three miles, emptying into the larger 

 stream at a distance below the pumping station of the Southeastern Hos- 

 pital for the Insane. 



It is along the baiiks and ou the sl()[)e to the south of Crooked creel: 



JH 



Fig. I. 



Ideal cross section of gravel bars and conglomerate deposits. Width of bar 

 a b equals one-fourth mile; height ^m n equals flO feet. 



(c) Red of Crooked creek. 



(d) Position of Ihickest c<ini,'l()in<'i-ali- and sandstone deposits, Irregularly 



placed. 



(e) and (s) Other h'regularly placed deposits of indurated rocks. 

 (a b) Low water mark Ohio river. 



