141:
129:
320:
abraded, indicating that they, at one time or another, occupied a subaerial environment. Almost all of the constituent grains were determined to have originated in Canada, and were carried southward by currents along the eastern shore of the
Paleozoic sea. This concept is supported by several lines of evidence: (1) the only plausible source of such a large volume of sand is in Canada at about 56° north latitude where
324:
sandstone was exposed extensively in
Ordovician time; (2) the base of the formation decreases in age from north to south as determined by marine fossils in subjacent beds; (3) the formation becomes finer grained from north to south apparently due to progressive abrasion of the grains along the way;
319:
Almost all of the constituent grains of the formation were deposited in a near-shore environment, mainly in shallow water, and to a much lesser extent on the beach as determined by the nature of bedding from place to place. The surfaces of the quartz grains are almost universally "frosted" or
278:
the formation extends more than 300 kilometres (190 mi) east-west, thinning out in both directions from maxima along its axis of more than 150 metres (490 ft). In Canada the east-west extent is much less but there also, it thins out to both east and west.
477:
Gehrels, G.E., Dickinson, W.R., Riley, B.C.D., Finney, S.C., and Smith, M.T. (2000). Detrital zircon geochronology of the
Roberts Mountains allochthon, Nevada, in Soreghan, M.J. and Gehrels, G.E., eds.,
229:, and that name is used almost exclusively in Nevada, but, in ensuing years, as extensions of the deposit were discovered in other areas, the same formation was given many other local names.
291:, which includes both the sand grains and the cement that binds them. The quartz cement accounts for its outstanding hardness and resistance to erosion. Minor constituents are grains of
339:
563:
334:
503:
266:, Mexico 950 kilometres (590 mi) south of its most southerly exposure in California, but that occurrence probably was tectonically displaced there from
528:
508:
498:
518:
553:
513:
538:
523:
558:
573:
543:
568:
199:
deposit in western North
America that is notable for its great extent, extreme purity, consistently fine grain size of
533:
548:
400:. Alberta Society of Petroleum Geologists, Canadian Sedimentary Basins Symposium, Chapter 4, part 2. pp. 42–48.
48:
262:, a north-south extent of about 2,200 kilometres (1,400 mi). An isolated exposure was identified in
58:
38:
287:
Cliff-forming quartzite, the principle part of the Eureka, is composed of more than 99 percent
480:
Paleozoic and
Triassic paleogeography and tectonics of western Nevada and northern California,
251:
112:
307:
are less than 1 mm (0.039 in) in diameter; those in Canada are slightly larger.
211:
222:
193:
169:
325:
and (4) the radiometric age of constituent zircon grains points to a northern source.
492:
449:
Petrology of the Eureka
Quartzite (Middle and Late Ordovician) Utah and Nevada U.S.A.
414:
Middle and Lower
Ordovician formations in southernmost Nevada and adjacent California
134:
24:
308:
482:
Special Paper 347. Boulder, Colorado: Geological
Society of America. pp. 19–42.
296:
267:
259:
218:
96:
28:
398:
Ordovician-Silurian of the
Cordillera in Geological History of Western Canada
207:
200:
196:
190:
81:
206:
The Eureka is commonly underlain and overlain by contrasting slope-forming
321:
300:
255:
203:, and its tendency to form conspicuous white cliffs visible from afar.
116:
270:. The Eureka and its correlatives are lenticular in cross-section: in
292:
288:
271:
263:
243:
226:
214:
146:
100:
247:
108:
384:. U.S. Geological Survey, Professional Paper 600-B. pp. 169–177.
382:
Origin of
Ordovician quartzite in the Cordilleran miogeosyncline
304:
275:
104:
311:
is believed to account for the scarcity of internal bedding.
242:
By whatever name, the Eureka can be traced, with gaps, from
468:. Alberta Society of Petroleum Geologists Journal 6: 61–68.
362:. U.S. Geological Survey, Third Annual Report. pp. 237–290.
416:. U.S. Geological Survey, Bulletin 1180-C. pp. C1–C101.
340:
List of fossiliferous stratigraphic units in California
335:
List of fossiliferous stratigraphic units in Nevada
175:
165:
160:
152:
122:
92:
87:
77:
72:
64:
54:
44:
34:
18:
462:Pre-Mississippian History of the Peace River Arch,
427:Eureka Quartzite in Mexico?--Tectonic implications
360:Geology of the Eureka Mining District, Nevada
8:
68:150 ft (46 m) (in southern Nevada)
564:Ordovician southern paleotropical deposits
15:
443:
441:
439:
437:
435:
392:
390:
376:
374:
372:
370:
368:
303:. All of the constituents in Nevada and
258:boundary, and southward to southeastern
504:Geologic formations of British Columbia
351:
408:
406:
7:
529:Ordovician System of North America
221:age. It was named in 1883 for the
14:
509:Geologic formations of California
466:Symposium on the Peace River Arch
451:Rocky Mountain Geology 47: 81–111
139:
127:
499:Geologic formations of Alberta
250:into western Canada along the
1:
519:Geologic formations of Nevada
156:2,200 km (1,400 mi)
554:Ordovician geology of Nevada
514:Geologic formations of Idaho
539:Ordovician British Columbia
524:Geologic formations of Utah
590:
559:Ordovician geology of Utah
412:Ross, R.J., Jr. (1964a).
380:Ketner, Keith B. (1968).
23:
460:deMille, George (1958).
425:Ketner, Keith B (1986).
574:Shallow marine deposits
429:. Geology 14: 1027–1030
447:McBride, E.F. (2012).
396:Norford, B.S. (1966).
358:Hague, Arnold (1883).
49:Hanson Creek Formation
544:Ordovician California
464:in Scott, J.C., ed.,
569:Quartzite formations
225:mineral district in
59:Copenhagen Formation
25:Stratigraphic range
534:Ordovician Alberta
246:northward through
39:Geologic formation
183:
182:
581:
549:Ordovician Idaho
483:
475:
469:
458:
452:
445:
430:
423:
417:
410:
401:
394:
385:
378:
363:
356:
252:British Columbia
189:is an extensive
187:Eureka Quartzite
145:
143:
142:
133:
131:
130:
113:British Columbia
19:Eureka Quartzite
16:
589:
588:
584:
583:
582:
580:
579:
578:
489:
488:
487:
486:
476:
472:
459:
455:
446:
433:
424:
420:
411:
404:
395:
388:
379:
366:
357:
353:
348:
331:
317:
299:and a trace of
285:
240:
235:
140:
138:
137:
128:
126:
115:
111:
12:
11:
5:
587:
585:
577:
576:
571:
566:
561:
556:
551:
546:
541:
536:
531:
526:
521:
516:
511:
506:
501:
491:
490:
485:
484:
470:
453:
431:
418:
402:
386:
364:
350:
349:
347:
344:
343:
342:
337:
330:
327:
316:
313:
284:
281:
239:
236:
234:
231:
181:
180:
177:
173:
172:
170:Eureka, Nevada
167:
163:
162:
158:
157:
154:
150:
149:
124:
120:
119:
94:
90:
89:
85:
84:
79:
75:
74:
70:
69:
66:
62:
61:
56:
52:
51:
46:
42:
41:
36:
32:
31:
21:
20:
13:
10:
9:
6:
4:
3:
2:
586:
575:
572:
570:
567:
565:
562:
560:
557:
555:
552:
550:
547:
545:
542:
540:
537:
535:
532:
530:
527:
525:
522:
520:
517:
515:
512:
510:
507:
505:
502:
500:
497:
496:
494:
481:
474:
471:
467:
463:
457:
454:
450:
444:
442:
440:
438:
436:
432:
428:
422:
419:
415:
409:
407:
403:
399:
393:
391:
387:
383:
377:
375:
373:
371:
369:
365:
361:
355:
352:
345:
341:
338:
336:
333:
332:
328:
326:
323:
314:
312:
310:
306:
302:
298:
294:
290:
282:
280:
277:
273:
269:
265:
261:
257:
253:
249:
245:
237:
232:
230:
228:
224:
220:
216:
213:
209:
204:
202:
198:
195:
192:
188:
178:
174:
171:
168:
164:
159:
155:
151:
148:
136:
135:United States
125:
121:
118:
114:
110:
106:
102:
98:
95:
91:
86:
83:
80:
76:
71:
67:
63:
60:
57:
53:
50:
47:
43:
40:
37:
33:
30:
26:
22:
17:
479:
473:
465:
461:
456:
448:
426:
421:
413:
397:
381:
359:
354:
318:
309:Bioturbation
286:
241:
205:
186:
184:
176:Year defined
161:Type section
283:Composition
233:Description
493:Categories
346:References
297:tourmaline
268:California
260:California
219:Ordovician
97:California
29:Ordovician
217:, all of
208:limestone
201:Quartzite
197:sandstone
191:Paleozoic
166:Named for
82:Quartzite
73:Lithology
65:Thickness
45:Underlies
329:See also
322:Cambrian
301:feldspar
212:dolomite
88:Location
55:Overlies
256:Alberta
123:Country
117:Alberta
78:Primary
315:Origin
293:zircon
289:quartz
272:Nevada
264:Sonora
244:Nevada
238:Extent
227:Nevada
223:Eureka
215:strata
194:marine
153:Extent
147:Canada
144:
132:
101:Nevada
93:Region
248:Idaho
109:Idaho
305:Utah
295:and
276:Utah
274:and
210:and
185:The
179:1883
105:Utah
35:Type
495::
434:^
405:^
389:^
367:^
107:,
103:,
99:,
27::
254:-
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.