Physical features of the Des Plaines Valley . ^„i*.««>«i^^. B. Exposure of Joliet conglomerate near Spring creek. UOLDTHWAIT.] GLACIAL AND INTER-GLACIAL DEPOSITS. 41 The chief deposits of gravel, which took place in the valleAs whicliwere the main lines of drainage while the ice was melting, are calledvalley trains. The Des Plaines valley from Lemont down past Jolietto Channahon, evidently received a thick deposit of this outwash, for itwas the main line of escape for the glacial waters with their over-burdenof rock Avaste. The original valley floor was built up b}^ these depositslocally so
Physical features of the Des Plaines Valley . ^„i*.««>«i^^. B. Exposure of Joliet conglomerate near Spring creek. UOLDTHWAIT.] GLACIAL AND INTER-GLACIAL DEPOSITS. 41 The chief deposits of gravel, which took place in the valleAs whicliwere the main lines of drainage while the ice was melting, are calledvalley trains. The Des Plaines valley from Lemont down past Jolietto Channahon, evidently received a thick deposit of this outwash, for itwas the main line of escape for the glacial waters with their over-burdenof rock Avaste. The original valley floor was built up b}^ these depositslocally some fifty feet. At the same time, tributary streams built branchvalley trains. Tliis was the case in the valleys of Long run. Fractionrun, Spring creek and Hickory creek (See Plate 5, A.) This process isijlustrated in Figs. 8 and 9. At a later time, when the ice sheet hadwithdrawn from the Valparaiso moraine, the over-loaded ice-fed streamin the Des Plaines valley was replaced by a river which issued from a
Size: 2295px × 1089px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookcentury1900, bookdecade1900, bookidphysicalfeatures00gold
