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The Yakima Fold Belt of south-central Washington, also called the Yakima fold-and-thrust belt, is an area of topographical folds (or wrinkles) raised by tectonic compression. It is a structural-tectonic sub province of the western Columbia Plateau Province resulting from complex and poorly understood regional tectonics. The folds are associated with geological faults whose seismic risk is of particular concern to the nuclear facilities at the Hanford Nuclear Reservation (immediately northwest of the Tri-Cities) and major dams on the Columbia and Snake Rivers. ==Location and extent== Image:Yakima Fold Belt map.jpg|right|thumb|upright=1.34|Shaded-relief map showing ridges of the Yakima Fold Belt of south-central Washington, mostly between Interstate 90 (red line) and the Columbia River (bottom). Red square in center is the city of Yakima, red rectangle at lower right is the Tri-Cities, red circles are various cities, triangles are the Mount Rainier, Mount Saint Helens, and Mount Adams volcanoes of the Southern Washington Cascades. Purple dashed line marks the approximate location of the Olympic-Wallowa Lineament (OWL), crossing the Columbia River at the Wallula Gap (lower-right). Orange dashed line is approximate location of edge of the North American craton. The smoothness of the central and eastern areas is due to infilling by volcanic flows of the Columbia River Basalts. # Image size: 641x458 (642x459) # # In error messages: imagemap line numbers include comment lines. # This should be line 5. # Areas defined first overlap areas defined later. (??) # Cities and towns: # Localized regions and lakes: circle 180 16 16 Lake Keechelus circle 204 24 20 Lake Kachess circle 224 34 16 Lake Cle Elum circle 254 56 16 Cle Elum circle 314 100 16 Ellensburg circle 434 48 16 Quincy circle 480 24 16 Ephrata circle 522 76 20 Moses Lake circle 506 92 20 Pot Holes Reservoir circle 538 140 16 Othello circle 320 200 16 Yakima circle 324 214 12 Union Gap circle 570 326 16 Wallula Gap circle 262 378 16 Goldendale circle 212 434 16 The Dalles circle 156 406 16 Hood River poly 1 30 12 32 12 46 1 46 Tacoma poly 510 264 558 264 558 292 510 292 Tri-Cities # circle 120 134 22 Mount Rainier circle 56 294 22 Mount Saint Helens circle 164 288 22 Mount Adams # Dams: poly 374 14 386 6 394 16 382 24 Rock Island Dam circle 408 134 16 Wanapum Dam circle 418 184 16 Priest Rapids Dam circle 582 278 16 Ice Harbor Dam circle 502 354 16 McNary Dam circle 290 402 16 John Day Dam circle 224 422 16 The Dalles Dam circle 102 408 16 Bonneville Dam # poly 72 48 140 52 160 90 152 122 142 126 146 108 132 64 88 66 White River # The Folds: poly 232 30 260 32 292 56 280 64 268 58 235 40 Cle Elum Ridge poly 238 64 252 60 278 74 274 82 260 74 244 74 South Cle Elum Ridge poly 224 80 242 82 286 104 306 106 378 144 380 160 298 118 272 118 232 100 Manastash Ridge poly 282 122 300 124 382 172 422 188 442 190 436 198 420 196 404 192 380 190 314 142 296 140 280 128 Umtanum Ridge poly 336 92 356 100 374 122 366 126 348 118 Boylston Mountains poly 382 2 410 2 396 20 Badger Mountain poly 404 22 422 2 478 2 470 30 406 32 Beezley Hills poly 364 130 376 126 420 138 470 138 520 146 548 166 540 178 514 160 418 156 392 148 Saddle Mountains poly 380 100 406 92 512 106 526 112 516 120 386 110 Frenchman Hills poly 470 184 494 188 502 206 594 208 472 198 Gable Mountain poly 250 124 266 126 284 148 290 158 278 158 254 142 Cleman Mountain poly 322 182 344 178 380 192 404 194 452 212 446 222 416 210 382 216 336 200 Yakima Ridge poly 210 166 352 150 268 162 246 176 226 174 Bethel Ridge poly 252 194 272 182 310 190 306 198 276 196 360 204 Cowiche Mountain poly 218 222 248 204 254 208 246 214 224 230 #Sedge Ridge poly 226 232 258 208 320 208 298 228 260 224 230 240 Ahtanum Ridge poly 232 210 248 208 380 220 412 216 446 230 464 230 480 256 436 274 334 218 Rattlesnake Hills poly 198 290 310 260 368 258 366 268 296 294 198 300 Toppenish Ridge poly 370 254 398 262 390 268 Snipes Mountain poly 314 324 394 306 474 274 515 309 546 310 552 320 542 326 496 320 468 304 402 328 330 330 Horse Heaven Hills circle 266 336 22 #Simcoe Mountain poly 300 334 352 334 344 346 294 348 #Bickleton Ridge poly 204 402 300 380 332 386 330 396 300 392 258 416 208 416 Columbia Hills (Washington) poly 448 352 466 338 512 330 510 346 470 350 454 356 #Paterson Ridge circle 492 266 16 #Red Mountain # Broader regions: poly 72 1 186 1 640 336 640 386 418 212 316 190 Olympic-Wallowa Lineament poly 510 109 528 100 612 334 594 334 #craton edge poly 296 2 322 2 380 52 392 188 376 182 366 98 356 60 304 24 #Naneum-Hog Ranch Anticline ### The topographical distinctness of the Yakima Folds (see the shaded-relief image) is due to their formation in a layer of lava flows and sedimentary deposits that have filled-in and generally smoothed the topographic surface of a large area of the Columbia Basin. The extent of these lava flows were limited to the west and north by the rising Cascade Mountains and the Wenatchee Mountains. The lava flows extend east well beyond the this image, but the Yakima Folds do not. The northern-most fold seen here〔Some researchers include structures north of this image.〕 (Frenchman Hills) ends at the Potholes Reservoir, another (Saddle Mountains) terminates just south of there, near the town of Othello (red circle). South of the Tri-Cities the rampart of the Horse Heaven Hills extends for a short distance past the Columbia River. The ends of these ridges mark the edge of a block of continental crust (part of the North American craton, indicated by the dashed orange line) that has resisted the tectonic compression that formed the ridges. The southernmost ridge of the Yakima Fold Belt is the Columbia Hills on the north side of the Columbia River. The pattern of folding continues with the Dalles-Umatilla Syncline just south of the Columbia River, and further into Oregon with the Blue Mountains anticline, which approximately parallels the Klamath-Blue Mountain Lineament that marks the southeastern edge of Siletzia (see geological map, below). The Yakima Fold Belt is also located on, and the orientation and spacing of some of the Folds influenced by, the Olympic-Wallowa Lineament (OWL), a broad zone of linear topographical features (dashed yellow line) extending from the Olympic Peninsula in northwestern Washington to the Wallowa Mountains in northeastern Oregon. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Yakima Fold Belt」の詳細全文を読む スポンサード リンク
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