AUGHET.] THE LOESS DEPOSITS. 247 



It will be seen from the above analyses of Biscliofif that l^os. 3 and 5, 

 in the quantity of silica and other elements that are present, come very 

 near the Loess of l!^ebraska. The principal difference is the larger quan- 

 tity of alumina present in the samples analyzed by Bischoft". Chemi- 

 cally the deposits of the Rhine Valley, as Hayden remarks, are not 

 essentially diiferent' from those of the Loess soils along the Missouri. 



As would be expected, from the elements which chemical analysis 

 shows to be present in these deposits, it forms one of the best soils in 

 the world. In fact, it can never be exhausted until every hill and valley 

 of which it is composed entirely worn away. Its drainage, which is the 

 best possible, is owing to the remarkably finejy-comminnted silica of 

 which the bulk of the deposit consists. Where the ground is cultivated 

 the most copious rains soon percolate through the soil, which, in its 

 lowest depths, retains it like a huge sponge. Even the unbroken prairie 

 absorbs much of the heavy rains that fall. When droughts come the 

 moisture comes up from below by capillary attraction. And when it is 

 considered that the depth to the solid rock ranges gene^lly from five 

 to two hundred feet, it is seen how readily the needs of vegetation are 

 supi^lied in the driest seasons. This is the main reason why over all the 

 region where these deposits prevail the natural vegetation and the well- 

 cultivated crops are rarely dried out or drowned out. I have frequently 

 observed a few showers to fall in April, and then no more rain until 

 June, when, as will be considered farther on, there is generally a rainy 

 season of from two to four weeks' continuance. After these June rains 

 little more would fall till autumn : and yet, if there was deep and 

 thorough cultivation, the crops of corn, cereals, and grass would be 

 most abundant. This condition represents the dry seasons. On the 

 other hand, the extremely wet seasons only damage the crops over the 

 low bottoms, subject to overflow. Owing to the siliceous nature of the 

 soils they never bake when plowed in a wet condition, and a day after 

 heavy rains the plow can again be successfully and safely used. 



The physical properties of the Lacustrine deposits are also remark- 

 able. In the interior, away from the Missouri, hundreds of miles of 

 these Lacustrine deposits are almost level or gently rolling. IN'ot unfre- 

 quently a region will be reached where, for a few miles, the country Is 

 bluffy or hilly, and then as much almost entirely level, with intermedi- 

 ate forms. The bluffs that border the flood-plains of the Missouri, the 

 Lower Platte, and some other streams are sometimes exceedingly pre- 

 cipitoHS, and sometimes gently rounded off. They often assume fantas- 

 tic forms, as if carved by some curious generations of the past. But 

 now they retain their forms so unchanged from year to year, affected 

 neither by rain nor frost, that they must have been molded into their 

 present outlines under circumstances of climate and level very differ- 

 ent from that which now prevails. 



For all purposes of architecture this soil, even for- the most massive 

 structures, is perfectly secure. I have never known a foundation of a 

 large brick or stone building, if commenced below the winter frost-line, 

 to give way. Even when the first layers of brick and stone are laid on 

 top of the ground there is seldom such unevenness of settling as 

 to produce fractures in the walls. On no other deposits, except 

 the solid rocks, are there such excellent roads. From twelve to 

 twenty-four hours after the heaviest rains the roads are perfectly 

 dry, and often appear, after being traveled a few days, like a vast floor 

 formed from cement, and by the highest art of man. The drawback to 

 this picture is that sometimes during a drought the air along the high 

 ways on windy days is filled with dust. And yet the soil is very easily 



