QUATERNARY AGE. — CHAMPLAIN PERIOD. 549 



width of the glacier that lay over the upper part of the great valley 

 west of the Appalachians, and the extent of local glacier centres in 

 the Rocky Mountains. Part of the transportation must have been due 

 to floating ice from the dissolving glacier. 



The "Orange sand" is -40 to 100 feet thick, and in some places over 200. Toward 

 the Gulf, it lies at considerable depth below the water level. In an Artesian well, near 

 the Calcasieu River (two hundred miles west of New Orleans), the Orange sand was 173 

 feet thick, beneath 160 of clay (Port Hudson group); and at another, seven hundred 

 yards to the west, 96 feet thick, beneath 354 feet of clay. These and the other facts 

 respecting the Orange sand are cited mainly from Hilgard's papers. In Tennessee, the 

 beds arc called by Safford the " Bluff gravel; " they overlie, in part, Eocene or Creta- 

 ceous beds, as they do also farther south. 



4. Alluvian Deposits. — The Diluvian beds along rivers and about 

 lakes are often overlaid by others, whose texture indicates more quiet 

 deposition. The floods were of long duration, owing to the very slow 

 retreat of the glaciers, and the continued depressed level of the land ; 

 and hence the lakes were still many and lar^e. and the rivers of great 

 breadth, though after a while somewhat diminished, from the lessened 

 supply of water. Floating ice from the north may long have aided in 

 transportation of earth and bowlders. Wherever the Diluvian forma- 

 tion was not built up to the level of the flood-waters, new beds were 

 deposited, mostly of earth or loam, making the alluvial beds or loess 

 of the river borders ; but, in other places, of sand and coarse material, 

 according to the rate of flow of the waters. 



Sand and fresh-water shells, teeth and bones of Quaternary Mam- 

 mals, leaves and other relics would naturally exist in deposits then 

 made ; and peat-beds may have been formed in marshes, and after- 

 ward become buried under new deposits in progress. 



Frequently, the Diluvian depositions filled the depression to the water level along the 

 sides of the valley (or lake basin), but left a wide area either side of the river bed at a 

 lower level; and over this part the Alluvian depositions were made, and the whole 

 finally brought up to one plain. These are points to be considered in judging of the 

 relative ages of the different parts of any Champlain deposit, whether fluvial, lacus- 

 trine, or marine. The loess is best developed on large streams. 



In the Mississippi valley, it covers the "Orange sand," forming with it the "Bluff 

 formation " — so called because standing in bluffs in Missouri and also on the east of 

 the Mississippi flats. In Tipton County, Tennessee, there are (over about ninety feet of 

 Lignitic Tertiary) 24 to 40 feet of Orange sand or "Bluff gravel," and 45 to 68 of Bluff 

 loam, or loess. (Safford.) The formation in Mississippi and Louisiana has been called 

 by Hilgard the "Port Hudson Group." It contains, like the loess of the Rhine, some 

 carbonate of lime, partly in concretions, due to fresh-water shells mixed in powder with 

 the earth. At intervals, it has layers of marsh material, including Cypress stumps im- 

 bedded in laminated clays ; and south of New Orleans there are marine shells. As the 

 Orange-sand deposits lie at considerable depth toward the Gulf, the Port Hudson de- 

 posit has a thickness in some places of several hundred feet; and, where this is the case, 

 the lower part may be the equivalent of a portion of the Orange sand. Above the Port 

 Hudson group, and a deposit overlying it, thirty to seventy feet thick, without bedding, 

 distinguished as " loess " by Hilgard, there is generally a thin deposit of yellow loam. 



