272 BUREAU OF AMERICAN ETHNOLOGY [BuU. 179 



did the laboratory analysis and was in charge of the preparation of 

 maps and drafting. Crabtree assisted in bringing together the mate- 

 rial that appears in the section headed "Previous work, discussion, 

 and critique" and in organizing the descriptions of chipped artifacts; 

 he also organized the Appendix. 



THE KEGION 



The best discussion of that part of the northwestern United States, 

 called the Plateau by anthropologists and the Columbia Intermontane 

 Province by physiographers, is to be found in the report by Freeman, 

 Forrester, and Lupher (1945). According to these writers Sheep 

 Island is in the Columbia Basin Subprovince, the Yakima Folds sec- 

 tion. The area is structurally a basin, surrounded by mountains. The 

 bedrock of the basin is probably Miocene basalt. In the Yakima Folds 

 section narrow ridges of upfolded basalt and equally narrow, down- 

 folded valleys alternate. These run east-west, extending east from 

 the Cascade Mountains. Of these sharp ridges the Horse Heaven 

 Hills extend the farthest east and are cut by the Columbia River at 

 the magnificent watergap called the Wallula Gateway. The Gateway 

 is some 9i/^ miles above Sheep Island. 



The topography is youthful ; the last uplift was Pleistocene and the 

 sediments are Pleistocene and Recent. Soil accumulations, except 

 flood plain material, are probably largely eolian. Flood plain accu- 

 mulations are uneven. Loamy fine sands (Harper et al., 1948) alter- 

 nate with areas of scabland and, close to the water, with remnants of 

 surface expressions of sand, gravel, and cobblestone bars. Away from 

 the flood plain the soils vary in depth and in the quality of the drain- 

 age. North of the Columbia River, m the region of Sheep Island, 

 the drainage in general is good, or perhaps too good ; the land stands 

 high above the water table, the soil mantle is thick, while to the south 

 the scablands are lower, the soil mantle thinner, and the water table 

 closer to the surface. Areas of alkali and numerous moisture-loving 

 plants indicate both poorer drainage and more water. 



The climate is continental, semiarid. The rain shadow of the Cas- 

 cades allows only enough rain and snow to fall during the winter to 

 permit a luxuriant spring and early summer growth of grasses, bush, 

 and weeds. Late summer and fall is a period of dryness and brown- 

 ing landscape. The years are usually temperate; summers are hot, 

 and subzeros winters are not unusual. 



In aboriginal times luxuriant grass growth appears to have covered 

 the floodplain and adjacent areas. Plowing and overgrazing have 

 brought about a change so that now bunchgrass and other grasses have 

 given way to bromegrass (or cheatgrass), mustard, Russian thistle, 

 etc. Sagebrush and rabbitbrush, too, have become components of the 

 new plant association. Planted trees, cottonwoods and poplars, and 



