219 



BENCH OR TERRACE DEPOSITS. 



These deposits have been described both by Mr. Siebenthal and Pro- 

 fessor Marsters. In spealving of them Mr. Siebenthal says: "Terraces 

 occur in the valley of Bean Blossom Creek above the crossing of the 

 drift limit. Drift deposits occur below that, but are irregular in height 

 and have not the level top of terraces. The terraces range from mere 

 knolls to benches a mile wide. The lower portions of these beds consist 

 of sand and erratic gravel with sand and smaller gravel above, and over 

 all sandy clay and loam. These terraces seem to have been deposited 

 by high waters which must have resulted from the melting of the glacier 

 which covered the head waters of the creek in Brown Ccmnty, and the 

 drainage of the glacier which crossed its lower course. The various 

 tributaries of Bean Blossom Creek have similar deposits in a smaller 

 way, the materials of which are, however, of local origin. The fact that 

 the drift material of foreign origin is confined to the creek itself, argues 

 that it was derived from the glacier occupying the upper course of the 

 creek." 



In speaking of the same terraces Professor V. F. Marsters says:* 



"Rimming the valley slopes are to be found a number of benches of 

 variable widths, with surfaces sometimes as flat as a floor or with an 

 exceedingly gentle decline valleyward, with outer edges lobate in shape 

 and descending with a marked angle to the level of the valley floor. These 

 occur at various points within the limits of Monroe County, invariably 

 situated on the north and east sidas of the valley, and varying in eleva- 

 tion from twenty feet in the lower part of the stream to seventy or more 

 feet in the upper part of the valley near the east line of Monroe County. 

 In all the cases examined they were found to be composed of mixtures 

 of clay and sand undoubtedly derived from the disintegrated rock forma- 

 tions constituting the surface of the uplands. No glacial debris of any 

 sort was found either on the surface or in any of the sections or cuts 

 in the benches noted within the limits of Monroe County." 



It will be readily seen that the two authors quoted above differ from 

 each other concerning the origin of the bench material. Mr. Siebenthal 

 says in svibstance, that it is of glacial origin; and Professor Marsters 

 gives a directly opposite view, stating that no glacial material of any 



'Proc. Ind. Acnd. Set. for 19 1, p. 225. 



