204 TOPOGRAPHICAL REPORT ON WESTERN DIVISION. 
the waters of its principal tributaries, Atahnam, Nahchess, &c., the country along the Yakima 
river from its sources in the mountains to its junction with the Columbia. From Ketetas north- 
erly to the mouth of the Pisquouse or Wenatshapam; thence, up the, Columbia to Fort 
Okinakane, the country on the Methow river from its head to its mouth, the country along the 
Okinakane river from its junction with the Columbia to the lakes beyond the forty-ninth parallel; 
thence, leaving the Okinakane at its forks, eastward across the country to the Nehoialpit river ; 
thence, down this river to its mouth, crossing the Columbia at Fort Colville. From Fort Colville 
to Fort Wallah-Wallah, via the valleys of the Slawntehus, Chemakane, Cherahna, and Wallah- 
Wallah rivers, crossing the Spokane river a few miles below the forks or site of the old Spokane 
house, and the Saptin or Lewis’ fork of the Columbia at the mouth of the Peluse; thence, down 
the south bank of the Columbia to the Dalles, and from the Dalles down the Columbia river 
by water to Fort Vancouver. 
The country gradually rises back of Vancouver into a light range of hills running parallel 
to Columbia river, and generally about a mile and a half from it. Two miles from Vancouver 
the trail crosses a brook twenty feet wide, which empties into a lake three miles below that 
place; the lake communicating with the Columbia ten miles below. From this stream the coun- 
try along the trail breaks into small openings or plains having no timber on them. They 
vary from a half to several miles in extent, are very level, as well as the adjacent country, 
and are separated from each other by narrow strips of woods. Kolsas, the largest of these 
plains, about seven miles from Vancouver, is six or seven miles long, and three or four in breadth, 
and connects on the south with a swampy arm of Camas plain, which stretches off to the east- 
ward, in which direction there is a large tract of the same character of country lying along Mill 
creek, and running down towards the Columbia. From Kolsas the trail bears to the northeast 
for six miles to a plain called Simsik, about a mile and a half long. The country between 
Vancouver and Simsik is similar in character—heavily timbered with fir, spruce, and a dense 
undergrowth of maple and hazel bushes. The soil is sandy and gravelly, especially the open 
plains ; the soil in the woods between Kolsas and Simsik is the best. The country up to 
Simsik is quite level; leaving Simsik east of north the country becomes hilly and broken along 
the trai], the hills becoming higher and more rocky as we approach the Cathlapoot’] river. 
Between these points the trail crosses several branches of the Cathlapoot’l. Six miles from 
Simsik there is a small rapid brook fifteen feet wide; two miles farther on there is another, thirty 
feet wide and two deep; and a third, the Yahkohtl, eight miles beyond, about forty feet wide 
and two and a half deep. The bottoms of these streams are rocky, and that of the Yahkohtl 
very stony; the currents rapid. They run among high hills, and have no valleys. They unite 
a short distance below the fords, the main stream uniting with the Cathlapoot’l four miles from 
its junction with the Columbia. Eleven and a half miles from the Yahkobtl the trail crosses 
the Chalacha. This river is thirty-five feet wide, ford good. It receives two branches a short 
distance below the ford—the first from the southeast, a bold rapid brook twenty feet wide; and 
the other a small rivulet coming in from the other side and running nearly parallel to the Chalacha, 
and one anda half or two miles from it. Thirteen miles from Simsik is Mankas Plain, surrounded 
by hills, and more low and swampy than the other plains met with. Six miles beyond the Yah- 
kohtl river is the Yahkohtl Plain, a high, sandy, undulating plain, about three miles long. Five 
and a half miles beyond this plain occurs the Chalacha Plain, lying between the Chalacha river and 
the parallel rivulet before spoken of The country between Mankas and Simsik is simply hilly; 
hills higher near the latter place. Between Mankas and the Yabkohtl river there are two sharp 
spurs of the Cascades, differing from the other hills by being higher and rocky. ‘They stretch off 
to the east and west, increasing in altitude towards the east, but falling off in the opposite direction. 
Between the Yahkohtl and Chalacha rivers the country is high and hilly, and, in places, much 
broken. There is a high spur running along the left bank of the Chalacha river, and the plain of 
this name is entirely surrounded by high ridges and rocky peaks. An almost perfectly symmetrical 
