620 OREGON. 
rated from the latter by a steep slope fifty or sixty feet in vertical 
height. ‘The dower prairie is sometimes four or five miles wide on 
either side of the river, and the stream flows through it with alluvial 
banks twenty or twenty-five feet high, except during freshets, when 
the waters overflow the banks, and the whole plain is often flooded. 
The border of the stream is usually a little higher than the country 
back. ‘The upper prairie extends sometimes to a distance of twelve 
or fifteen miles from the river, and is occasionally cut through by 
gullies or valleys, and reduced to a succession of low hills. 
The grass of these prairies is in scattered tufts, one tuft every eigh- 
teen or twenty inches, and it is usually eighteen to twenty-four inches 
high. It grows so thinly that “a prairie on fire” is no very terrific 
spectacle. With a few green branches, the fires, at any time, may be 
brushed out. A line of flame creeps along slowly over the field, 
blazing up only a foot or two, and smoking abundantly, but leaving 
unhurt the larger shrubs and the coarser green grass or sedge along 
the rivulets. 
The Willammet district abounds in lands fitted both for tillage and 
pasturage. The soil of the lower prairie is, in general, a light allu- 
vial loam, which becomes dry and dusty during the summer droughts. 
It has not the usual mellowness of the bottom-lands of our western 
rivers on the eastern side of the mountains, and apparently for the 
reason that the stream flows through a dry region, which can contri- 
bute little comparatively that is nutritious to the waters. Yet the 
grass, though thin, is excellent, and the soil affords profitable crops. 
The upper prairie has commonly a more clayey soil about the Wil- 
lammet settlement, and forms a deep adhesive mud in the rainy season, 
which becomes so hardened in the summer sun as scarcely to receive 
any impression from the hoofs of horses. Yet the proportion of clay 
is not such as to render it sterile, and it is generally preferred for 
tillage. In some places it is sufficiently plastic for brick-making. 
The peculiarities of the upper and lower prairies are by no means 
constant, and the characters here given to one sometimes belong to the 
other. In the vicinity of basaltic rocks the soil is often of a dark 
chocolate colour, and is loose and highly fertile, while near the argil- 
laceous sandstone hills, it is of a dirty grayish colour, and often stiff 
and clayey, sometimes so barren as to produce nothing but stinted 
ferns. Pebbles of agate, chalcedony and carnelian are strewed 
along the streams, and in some places are scattered over the prairies. 
The loose basaltic soil at times opens in deep cracks on drying, which 
