366 Chamfoerlin and Salisbury — jRelationship of 



It is a peculiarity of the distribution of loess, that elevations 

 within the area of its occurrence seem to be no obstacle to its 

 presence. The loess is quite as likely to find its normal devel- 

 opment on the higher lands as on the lower. Within the area 

 especially under consideration, the same may be said concern- 

 ing the gravels. They exist on the highest hills, under the 

 loess, and in fact, speaking generally, find there their best de- 

 velopment. The gravels are frequently absent from the slopes 

 of the hills, or but meagerly developed upon them, even when 

 present in quantity upon their crests. These sands and gravels, 

 or at least the portion of them known under the name of 

 Orange Sand (Hilgard), have heretofore generally been re- 

 garded as Quaternary, and have even been referred 6 to the 

 Champlain epoch. * 



We have already seen, however, that the evidence is con- 

 clusive that the loess is to be referred to the melting waters of 

 the first glacial epoch, and the Orange Sand, so far from being 

 referred to a time subsequent to the second glacial epoch, must 

 be referred to a time earlier than the closing stages of the first 

 glacial. How much earlier ? 



It would not be irrational to suppose that the waters of the 

 melting ice might carry down, along the courses which they 

 followed, great quantities of detritus. Gravel and sand might 

 thus be distributed wherever the currents were strong enough 

 to carry them, conceivably for great distances south of the 

 limit of ice advance, just as gravels are carried far beyond the 

 ends of glaciers to-day by the streams issuing from them. 

 The Mississippi valley must have been an avenue for the dis- 

 charge of glacio-natant waters, and it would not be strange 

 were glacial gravels found in the same, beyond the extra-valley 

 drift limit, just as glacial gravels, originating from the ice of 

 the second epoch, are found down the valleys far beyond the 

 limit of ice advance at that time. Were the Orange sands and 

 gravels formed in the manner above indicated, and at the time 

 which this origin would necessitate, viz : in the first glacial 

 epoch, we might find evidence of the fact along three several 

 lines, any one of which would be conclusive. 



If the gravels be referable to the time of glaciation immedi- 

 ately preceding the deposit of the loess, we should find the 

 loess spread over these gravels conformably, or with only such 

 slight unconformity as might have been developed locally in 

 the interval between the deposition of the gravels, when the 



* Hilgard : Agriculture and Geology of Mississippi, 1 860. Also this Journal, vol. 

 xli, page 311, 1866. Safford: Ibid, vol. xxvii, page 361, 1864. Dana: Manual 

 of Geology, 3d edition, page 54.8. LeConte's Elements of Geology, page 540. 

 Loughridge: Kentucky Geol. Surv. Jackson Purchase Region, 1888, page 57 et 

 seq. By the Geological Survey of Illinois, the formation in question has been re- 

 garded as Tertiary. Yol i, page 417, et seq., and page 447, et seq. 



