405:
beyond the
Missouri River, with an uncertain age, often thought to be the Wisconsin glaciation. The Brookings till plain is a belt of heavily weathered ground moraine, running through Brookings. Dating to the Illinoisan, it escaped burial by the Wisconsin ice sheet. A narrow strip in the central Prairie Hills holds the Toronto till plain, the oldest definitively Wisconsin drift, while the Bemis stage on the eastern edge of the hills formed a belt of moraines. Although the ice did not advance east of the Prairie Hills, it left a remaining moraine ridge, known as the Altamont stage, which encroaches the western side of the hills. Late in the Wisconsin, the ice sheet divided at the Prairie Hills, extending the Des Moines lobe to the east and a western lobe along the James River valley. A final advance of the glacier, known as the Big Stone stage, traced the Minnesota River lowland in the northeast.
1704:
19:
344:, the Black Hills eroded, shedding debris into the east, during a period with sub-tropical temperatures. Iron pyrite in shales oxidized, becoming bright red and yellow iron oxides. Sediments did not accumulate in the region until the end of the Eocene, as large streams carried material away to the ocean. Volcanic rocks from the Eocene preserve petrified trees.
389:, but the period came with a return to warm and wet conditions. Revitalized streams carried away large amounts of sediments, wiping out much of the White River Formation. Hundreds of feet of younger sediment cover the White River group in southwest South Dakota. Miocene sandstones, which often form cliffs, often overlay the White River Formation.
378:
jagged pinnacles of the
Badlands. By the late 1990s, paleontologists had discovered 150 genera of mammals, ranging between rodents and rhinoceroses, as well as horses and camels. At the end of its five million year deposition, the formation was capped with the brilliantly white Rocky Ford ash, the windfall from powerful
356:, while some erosion occurred in the east. Gravel deposits containing crocodile bones and land snails, tortoises and hackberry seeds are also common in the fossil record. Bird bones and even fossil duck eggs have been found in association with clams, snails and the remains of algal mats in temporary ponds.
167:
formed during this period, exposed as a 400-foot thick unit in the walls of the
Spearfish Canyon, ranging to 50 feet thick by Wind Cave. Cambrian rocks are only exposed in the Black Hills and disappear in boreholes drilled to the south of Wind Cave, beyond the ancient shoreline. However, the Deadwood
404:
ice ages, South Dakota experienced multiple sequences of glaciation. The oldest glacial drift deposits are in the southeast, at Sioux Falls and Newton Hills, overlain by deeply weathered
Illinoisan, or potentially pre-Illinoisan age material. A large expanse of till fills the James River lowland and
377:
encompasses clay laid down by water, windblown sand, silt and volcanic ash, with a maximum thickness of up to 450 feet. Desert caliche soils are sometimes preserved as lime nodules and small clay buttes are often capped by well-cemented channel sands and gravels. The Brule
Formation erodes into the
425:
until its closure in 2002, merged the
Deadwood, Golden Terra, Father DeSmet and Caledonia gold mines around 1900. Its employees used emerging pneumatic drill technology and cyanide processing, creating the Ross Shaft and Yates Shaft—both 5000 feet deep—by 1941. Mine activity was suspended during
246:, depositing thick sequences of black Pierre shale—the thickest and most widespread sedimentary unit in the state. Originally, the shale ranged between 2500 feet thick at the Wyoming line and only tens of feet thick in the east, although erosion stripped it away in the Black Hills. The
456:
in the northwest, although it produces only one percent of the US total, primarily from traditional vertical wells. One hundred wells produce 1.6 million gallons of oil annually. Almost all production is centered in a 400 square mile area within
Harding County, relying on the
269:
began to recede, 15 million years after the Pierre shale first started to form. Low permeability shale yielded a poorly drained landscape, cut streams and rivers, which brought in large amounts of sediment—clay, silt and sand up to 500 feet thick—which deposited as the
351:
brought a shift in the climate to arid conditions, transforming the region into a vast alluvial desert plain. Up to 600 feet of sands and clays, buried the Black Hills within 2000 feet of their crests in western South Dakota, forming the
363:
is the lower unit, covering over the oxidizing Eocene erosion surface and reaching up to 180 feet thick. The thickness of the formation varies widely, where it fills into pre-existing valleys or blankets hills. It contains light-green
321:
is up to 350 feet thick and in the northwest contains no obvious break in continental deposition at the time of the mass extinction, except for being sandier and less well-cemented. Further east, the formation contains the subsidiary
1740:
372:
fossils and other large mammals have been found in the formation. Due to the high concentration of clay and the ease with which it erodes, the
Chadron Formation tends to form gentle sloping hills and buttes. The overlying
171:
The
Deadwood Formation is beach sand and gravel at its base, but as the ancient shoreline moved eastward, thin layers of mudstone and limestone formed in the west, in deeper waters. The formation contains
1733:
261:
bones. Tepee buttes form as small, conical hills in the Pierre shale landscape, from lenses of more erosion resistant limestone. Beach sand coal sequences left behind as the up to 200 feet thick
426:
World War II and resumed. By the mine's centennial in 1976, it was 8000 feet deep and had produced 31 million ounces of gold, seven million ounces of silver and 115 million tons of milled ore.
1726:
741:
163:, as limestone, sandstone and shale deposited. The Sioux quartzite was likely the only point of high topography, rising above a flat plain which was invaded with seawater. The
846:
2105:
780:
297:
66 million years ago. Below the boundary clay, fossil pollen from large fields is common, but pollen is uncommon for a long period in the record afterward.
2061:
703:
151:
in parallel with the rapid proliferation of multi-cellular life, terrestrial erosion continued in the region. The area was flooded during a large scale
326:, deposited during a brief resurgence of the inland sea and bearing fossil oysters, snails and clams. The 300 feet of sandstone and lignite of the
2051:
670:
434:
2071:
873:
758:
103:, active until 2002, was a major gold mine that reached up to 8000 feet underground and is now used for dark matter and neutrino research.
1614:
775:
1301:
790:
293:
Like many other locations around the world, South Dakota preserves the inch thick boundary clay, left by the asteroid impact of the
200:, widespread terrestrial erosion affected all but the north-central part of the state. Additional limestone deposits formed in the
330:
overlies the Ludlow
Formation, getting thicker to the east and holding some of the major coal deposits found in northern Wyoming.
119:, over 2.5 billion years ago. The Archean crystalline basement rock formed with the intrusion of the Little Elk and Bear Mountain
2100:
2033:
1414:
1356:
770:
726:
421:, lead, zinc, uranium, lithium and sand, as well as oil, beginning in the 1870s. The Homestake Mining Company, which managed the
1809:
1619:
1524:
1474:
1321:
1604:
1584:
1549:
1429:
1384:
1379:
1206:
1041:
936:
795:
721:
716:
368:
clay, with a high shrink-swell capacity, as well as lenses of limestone containing snail, clam and algae remains from ponds.
91:
and storing marine and mammal fossils. Much of the state's landscape was reworked during several phases of glaciation in the
1994:
1679:
1594:
1574:
1559:
1409:
1326:
785:
422:
100:
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1649:
1639:
1634:
1624:
1564:
1539:
1534:
1514:
1489:
1469:
1464:
1444:
1399:
1374:
831:
2025:
1919:
1669:
1629:
1579:
1519:
1509:
1499:
1494:
1439:
1434:
1369:
1364:
1311:
951:
858:
1674:
1664:
1654:
1644:
1609:
1599:
1589:
1569:
1544:
1484:
1479:
1459:
1454:
1419:
1404:
1394:
1389:
1341:
1316:
1306:
736:
663:
2079:
2041:
1959:
1924:
1659:
1554:
1529:
1504:
1424:
1246:
1166:
1131:
1116:
1111:
1076:
1001:
926:
911:
746:
731:
1999:
1904:
1864:
1449:
1336:
1146:
1086:
1021:
996:
971:
853:
816:
811:
763:
253:
West of the Missouri River, the Niobrara chalk formed in the inland sea during the Cretaceous, which contains
413:
The Black Hills were extensively explored and periodically mined for silver, gold, mica, tungsten, feldspar,
1954:
1949:
1929:
1296:
1286:
1251:
1141:
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1121:
1061:
1026:
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956:
821:
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711:
266:
205:
193:
68:
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1879:
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1241:
1231:
1221:
1216:
1201:
1161:
1106:
986:
946:
881:
327:
177:
22:
95:. South Dakota has extensive mineral resources in the Black Hills and some oil and gas extraction in the
1914:
1909:
1784:
1346:
1271:
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1196:
1186:
1151:
1136:
1101:
1066:
1031:
1011:
981:
961:
901:
826:
656:
353:
334:
87:, followed by long-running periods of erosion, sediment deposition and volcanic ash fall, forming the
2004:
1969:
1874:
1849:
1718:
1331:
1276:
1266:
1226:
1211:
1191:
1181:
1176:
1156:
1096:
1091:
1071:
1056:
1051:
991:
693:
323:
294:
271:
152:
1989:
1939:
1894:
1884:
1869:
1859:
1844:
1824:
1799:
1789:
1779:
1708:
1261:
1236:
1081:
976:
916:
891:
458:
262:
201:
2009:
1984:
1889:
1829:
1804:
1774:
1764:
1171:
629:
446:
164:
1944:
1899:
1839:
1814:
1769:
1016:
360:
2019:
1974:
1854:
1819:
397:
333:
In the northwest, the Ludlow, Cannonball and Tongue River formations are categorized as the
318:
247:
76:
2046:
1979:
1934:
1834:
896:
453:
374:
189:
96:
599:
574:
359:
Since the 1800s, geologists have debated how to subdivide the White River Formation. The
396:. Particularly in western South Dakota, the mobilization of coarse sediments formed the
132:
628:
Driscoll, Daniel G.; Carter, Janet M.; Williamson, Joyce E.; Putnam, Larry D. (1990).
2094:
906:
369:
286:
197:
156:
863:
841:
836:
683:
242:, with extensive erosion, and then returned to a shallow marine environment in the
31:
886:
438:
401:
317:. The Pierre shale east of the Black Hills eroded into an undulating plain. The
306:
280:
128:
116:
92:
80:
44:
40:
18:
679:
258:
243:
209:
160:
72:
219:, marked by erosion in the east and continued marine deposition in the west.
180:
is also common, resulting from fragments of limestone broken up in waves The
921:
430:
414:
365:
348:
310:
173:
148:
56:
48:
442:
393:
379:
314:
254:
239:
235:
231:
227:
185:
181:
144:
120:
88:
84:
64:
60:
648:
176:
fossils and tracks left by worms, exposed at low tide. Intraformational
131:
and the Harney Peak granite emplaced around 1.71 billion years ago. The
386:
275:
216:
123:, with interceding periods of volcanic activity, mountain building and
112:
36:
341:
168:
Formation reaches a thickness of 700 feet in wells in the northwest.
43:. Igneous crystalline basement rock continued to emplace through the
135:
was marked by a long period of erosion in the stratigraphic record.
71:
flooded the region, creating vast shale, chalk and coal beds in the
418:
188:
were marked by more carbonate deposition, particularly within the
124:
52:
127:
deposition. Marine sandstones and clays and deposited during the
449:, there is still an active open pit gold mine, run by Goldcorp.
385:
Smaller volumes of light-colored sand and clay deposited in the
337:, with thick sandstone layers sourced from the Rocky Mountains.
1722:
652:
250:
began the uplift of the Rocky Mountains during the Cretaceous.
561:
549:
47:, interspersed with sediments and volcanic materials. Large
59:, during prevalent shallow marine conditions, followed by
437:, the largest underground laboratory in the US, used for
392:
A period of erosion occurred in South Dakota during the
305:
Following the retreat of the Cretaceous inland sea, the
600:"Industry Facts - South Dakota Oil and Gas Association"
278:
beds, along with dinosaur bones, most notably those of
238:. The region returned to terrestrial conditions in the
309:
were uplifted, accompanied by igneous activity in the
35:
began to form more than 2.5 billion years ago in the
2070:
2032:
2018:
1757:
1355:
1285:
1040:
935:
872:
804:
702:
630:"Hydrology of the Black Hills Area, South Dakota"
433:site, although the shafts are now reused for the
452:South Dakota has oil and gas production in the
1734:
664:
429:After its closure, the location was deemed a
382:eruptions in the Western Cascades in Oregon.
111:The oldest rocks in South Dakota date to the
8:
107:Stratigraphy, tectonics and geologic history
192:, east to central South Dakota. During the
1741:
1727:
1719:
671:
657:
649:
204:. A marine environment prevailed in the
17:
470:
301:Cenozoic (66 million years ago-present)
230:formed throughout the west, during the
79:began to form the Rocky Mountains. The
2106:Geology of the United States by state
537:
525:
513:
501:
489:
477:
435:Sanford Underground Research Facility
139:Paleozoic (541–251 million years ago)
63:during terrestrial conditions in the
7:
644:. Mountain Press Publishing Company.
14:
1702:
642:Roadside geology of South Dakota
579:www.mininghistoryassociation.org
208:, as sandstones, carbonates and
223:Mesozoic (251–66 million years)
274:. The formation contains thin
1:
575:"South Dakota Mining History"
1750:Geology of the United States
1042:Smaller incorporated places
937:Larger incorporated places
83:were uplifted in the early
55:deposits formed during the
2122:
215:Sea levels receded in the
1698:
847:Colleges and universities
690:
640:Gries, John Paul (1996).
2052:Northern Mariana Islands
409:Natural resource geology
2101:Geology of South Dakota
1709:South Dakota portal
445:research. Southwest of
267:Western Interior Seaway
69:Western Interior Seaway
328:Tongue River Formation
234:, at the start of the
147:, at the start of the
25:
23:Badlands National Park
1752:by political division
902:Dissected Till Plains
727:Famous South Dakotans
354:White River Formation
21:
562:Driscoll et al. 1990
550:Driscoll et al. 1990
324:Cannonball Formation
313:at the start of the
295:K-Pg mass extinction
272:Hell Creek Formation
153:marine transgression
2062:U.S. Virgin Islands
1302:Colonial Pine Hills
892:Coteau des Prairies
781:Tourist attractions
459:Red River Formation
263:Fox Hills Formation
202:Early Mississippian
1044:pop. 1,000 - 5,000
786:Towns and villages
516:, p. 191–197.
492:, p. 205–210.
447:Lead, South Dakota
165:Deadwood Formation
26:
2088:
2087:
1716:
1715:
1322:North Eagle Butte
361:Chadron Formation
2113:
2072:Outlying islands
2026:Washington, D.C.
2020:Federal district
1743:
1736:
1729:
1720:
1707:
1706:
1705:
1207:North Sioux City
673:
666:
659:
650:
645:
636:
634:
615:
614:
612:
610:
596:
590:
589:
587:
585:
571:
565:
559:
553:
547:
541:
535:
529:
523:
517:
511:
505:
504:, p. 93–96.
499:
493:
487:
481:
475:
398:Ogallala aquifer
335:Fort Union Group
319:Ludlow Formation
248:Laramide orogeny
77:Laramide orogeny
2121:
2120:
2116:
2115:
2114:
2112:
2111:
2110:
2091:
2090:
2089:
2084:
2066:
2028:
2014:
1753:
1747:
1717:
1712:
1703:
1701:
1694:
1351:
1327:North Spearfish
1289:pop. over 1,000
1288:
1281:
1043:
1036:
939:pop. over 5,000
938:
931:
897:Missouri Coteau
868:
800:
698:
686:
677:
639:
632:
627:
624:
619:
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520:
512:
508:
500:
496:
488:
484:
476:
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467:
454:Williston Basin
411:
375:Brule Formation
340:Throughout the
303:
225:
190:Williston Basin
141:
109:
97:Williston Basin
12:
11:
5:
2119:
2117:
2109:
2108:
2103:
2093:
2092:
2086:
2085:
2083:
2082:
2080:Howland Island
2076:
2074:
2068:
2067:
2065:
2064:
2059:
2054:
2049:
2044:
2042:American Samoa
2038:
2036:
2030:
2029:
2024:
2022:
2016:
2015:
2013:
2012:
2007:
2002:
1997:
1992:
1987:
1982:
1977:
1972:
1967:
1962:
1960:South Carolina
1957:
1952:
1947:
1942:
1937:
1932:
1927:
1925:North Carolina
1922:
1917:
1912:
1907:
1902:
1897:
1892:
1887:
1882:
1877:
1872:
1867:
1862:
1857:
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1507:
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1497:
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1477:
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1467:
1462:
1457:
1452:
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1437:
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1427:
1422:
1417:
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1407:
1402:
1397:
1392:
1387:
1382:
1377:
1372:
1367:
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1244:
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1234:
1229:
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1219:
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1209:
1204:
1199:
1194:
1189:
1184:
1179:
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1169:
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1129:
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1119:
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1109:
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1074:
1069:
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1038:
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1024:
1019:
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984:
979:
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856:
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849:
839:
834:
829:
824:
819:
814:
808:
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802:
801:
799:
798:
796:Transportation
793:
788:
783:
778:
773:
768:
767:
766:
761:
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750:
749:
744:
734:
729:
724:
722:Climate change
719:
714:
708:
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591:
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494:
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469:
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423:Homestake Mine
410:
407:
302:
299:
224:
221:
196:period of the
140:
137:
133:Neoproterozoic
108:
105:
101:Homestake Mine
13:
10:
9:
6:
4:
3:
2:
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2037:
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2031:
2027:
2023:
2021:
2017:
2011:
2008:
2006:
2003:
2001:
2000:West Virginia
1998:
1996:
1993:
1991:
1988:
1986:
1983:
1981:
1978:
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1971:
1968:
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1931:
1928:
1926:
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1918:
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1911:
1908:
1906:
1905:New Hampshire
1903:
1901:
1898:
1896:
1893:
1891:
1888:
1886:
1883:
1881:
1878:
1876:
1873:
1871:
1868:
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1865:Massachusetts
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1678:
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1663:
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1658:
1656:
1653:
1651:
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1646:
1643:
1641:
1638:
1636:
1633:
1631:
1628:
1626:
1623:
1621:
1618:
1616:
1615:Oglala Lakota
1613:
1611:
1608:
1606:
1603:
1601:
1598:
1596:
1593:
1591:
1588:
1586:
1583:
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1578:
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1573:
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1568:
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1501:
1498:
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1473:
1471:
1468:
1466:
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1426:
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1398:
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1325:
1323:
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1318:
1315:
1313:
1312:Fort Thompson
1310:
1308:
1305:
1303:
1300:
1298:
1295:
1294:
1292:
1290:
1287:Largest CDPs
1284:
1278:
1275:
1273:
1270:
1268:
1265:
1263:
1260:
1258:
1255:
1253:
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1128:
1125:
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1103:
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1003:
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985:
983:
980:
978:
975:
973:
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968:
965:
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960:
958:
955:
953:
952:Belle Fourche
950:
948:
945:
944:
942:
940:
934:
928:
925:
923:
920:
918:
915:
913:
910:
908:
907:Drift Prairie
905:
903:
900:
898:
895:
893:
890:
888:
885:
883:
880:
879:
877:
875:
871:
865:
862:
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857:
855:
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848:
845:
844:
843:
840:
838:
835:
833:
830:
828:
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823:
820:
818:
815:
813:
810:
809:
807:
803:
797:
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792:
789:
787:
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779:
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774:
772:
769:
765:
762:
760:
757:
756:
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752:
748:
745:
743:
740:
739:
738:
735:
733:
730:
728:
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723:
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718:
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689:
685:
681:
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631:
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621:
605:
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580:
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567:
563:
558:
555:
551:
546:
543:
540:, p. 17.
539:
534:
531:
527:
522:
519:
515:
510:
507:
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483:
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427:
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416:
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403:
399:
395:
390:
388:
383:
381:
376:
371:
370:Titanotherium
367:
362:
357:
355:
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345:
343:
338:
336:
331:
329:
325:
320:
316:
312:
308:
300:
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296:
291:
289:
288:
287:Tyrannosaurus
283:
282:
277:
273:
268:
264:
260:
256:
251:
249:
245:
241:
237:
233:
229:
222:
220:
218:
213:
211:
207:
206:Pennsylvanian
203:
199:
198:Carboniferous
195:
194:Mississippian
191:
187:
183:
179:
175:
169:
166:
162:
158:
157:Late Cambrian
154:
150:
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138:
136:
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126:
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114:
106:
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98:
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70:
66:
62:
58:
54:
50:
46:
42:
38:
34:
33:
24:
20:
16:
2057:Puerto Rico
1965:South Dakota
1964:
1955:Rhode Island
1950:Pennsylvania
1930:North Dakota
1700:
1342:Rapid Valley
1317:Green Valley
1307:Dakota Dunes
832:Demographics
759:Bibliography
692:
684:South Dakota
641:
622:Bibliography
607:. Retrieved
603:
594:
582:. Retrieved
578:
569:
564:, p. 2.
557:
545:
533:
528:, p. 3.
521:
509:
497:
485:
473:
451:
428:
412:
391:
384:
358:
346:
339:
332:
304:
292:
285:
279:
252:
226:
214:
178:conglomerate
170:
159:through the
142:
110:
32:South Dakota
29:
27:
15:
2034:Territories
1880:Mississippi
1795:Connecticut
1415:Charles Mix
1247:Springfield
1167:Hot Springs
1132:Fort Pierre
1117:Eagle Butte
1112:Dell Rapids
1077:Chamberlain
1002:Sioux Falls
887:Black Hills
859:LGBT rights
771:State Parks
742:Delegations
439:dark matter
402:Pleistocene
307:Black Hills
281:Triceratops
212:deposited.
129:Proterozoic
117:Precambrian
115:eon of the
93:Pleistocene
81:Black Hills
45:Proterozoic
41:Precambrian
39:eon of the
30:geology of
2095:Categories
1995:Washington
1915:New Mexico
1910:New Jersey
1785:California
1620:Pennington
1525:Hutchinson
1475:Fall River
1337:Pine Ridge
1147:Gettysburg
1087:Clear Lake
1022:Vermillion
997:Rapid City
972:Harrisburg
927:West River
917:Pine Ridge
912:East River
737:Government
538:Gries 1996
526:Gries 1996
514:Gries 1996
502:Gries 1996
490:Gries 1996
478:Gries 1996
465:References
400:. In the
265:after the
259:plesiosaur
244:Cretaceous
210:evaporites
161:Ordovician
73:Cretaceous
2005:Wisconsin
1970:Tennessee
1875:Minnesota
1850:Louisiana
1605:Minnehaha
1585:McPherson
1550:Kingsbury
1430:Codington
1385:Brookings
1380:Bon Homme
1297:Blackhawk
1252:Summerset
1142:Garretson
1127:Flandreau
1122:Elk Point
1062:Beresford
1027:Watertown
1007:Spearfish
967:Brookings
957:Box Elder
922:Siouxland
842:Education
791:Townships
747:Elections
732:Geography
697:(capital)
604:sdoil.org
431:Superfund
415:bentonite
366:bentonite
349:Oligocene
311:Paleocene
174:trilobite
149:Paleozoic
57:Paleozoic
49:limestone
1990:Virginia
1940:Oklahoma
1920:New York
1895:Nebraska
1885:Missouri
1870:Michigan
1860:Maryland
1845:Kentucky
1825:Illinois
1800:Delaware
1790:Colorado
1780:Arkansas
1680:Walworth
1595:Mellette
1575:Marshall
1560:Lawrence
1410:Campbell
1357:Counties
1242:Sisseton
1232:Redfield
1222:Piedmont
1217:Parkston
1202:Mobridge
1162:Hartford
1107:Deadwood
987:Mitchell
947:Aberdeen
882:Badlands
864:Politics
854:Gun laws
817:Cannabis
812:Abortion
764:Timeline
443:neutrino
394:Pliocene
380:rhyolite
315:Cenozoic
255:mosasaur
240:Jurassic
236:Mesozoic
232:Triassic
228:Red beds
186:Devonian
182:Silurian
145:Cambrian
121:granites
89:Badlands
85:Cenozoic
65:Triassic
61:red beds
2010:Wyoming
1985:Vermont
1890:Montana
1830:Indiana
1810:Georgia
1805:Florida
1775:Arizona
1765:Alabama
1690:Ziebach
1685:Yankton
1650:Stanley
1640:Sanborn
1635:Roberts
1625:Perkins
1565:Lincoln
1540:Jerauld
1535:Jackson
1515:Harding
1490:Gregory
1470:Edmunds
1465:Douglas
1445:Davison
1400:Buffalo
1375:Bennett
1347:Rosebud
1272:Webster
1257:Tyndall
1197:Mission
1187:Milbank
1152:Gregory
1137:Freeman
1102:De Smet
1067:Britton
1032:Yankton
1012:Sturgis
982:Madison
962:Brandon
874:Regions
837:Economy
822:Culture
805:Society
776:Symbols
754:History
712:Outline
635:. USGS.
387:Miocene
276:lignite
217:Permian
155:in the
143:In the
113:Archean
75:as the
37:Archean
1945:Oregon
1900:Nevada
1840:Kansas
1815:Hawaii
1770:Alaska
1758:States
1670:Turner
1630:Potter
1580:McCook
1520:Hughes
1510:Hanson
1500:Hamlin
1495:Haakon
1440:Custer
1435:Corson
1370:Beadle
1365:Aurora
1332:Oglala
1277:Winner
1267:Wagner
1227:Platte
1212:Parker
1192:Miller
1182:Lennox
1177:Lemmon
1157:Groton
1097:Custer
1092:Crooks
1072:Canton
1057:Baltic
1052:Aurora
992:Pierre
717:Cities
704:Topics
694:Pierre
609:7 July
584:7 July
342:Eocene
99:. The
67:. The
1975:Texas
1855:Maine
1820:Idaho
1675:Union
1665:Tripp
1655:Sully
1645:Spink
1610:Moody
1600:Miner
1590:Meade
1570:Lyman
1545:Jones
1485:Grant
1480:Faulk
1460:Dewey
1455:Deuel
1420:Clark
1405:Butte
1395:Brule
1390:Brown
1262:Volga
1237:Salem
1082:Clark
977:Huron
827:Crime
680:State
633:(PDF)
419:beryl
125:shale
53:shale
2047:Guam
1980:Utah
1935:Ohio
1835:Iowa
1660:Todd
1555:Lake
1530:Hyde
1505:Hand
1425:Clay
1172:Lead
611:2018
586:2018
441:and
347:The
284:and
257:and
184:and
51:and
28:The
1450:Day
1017:Tea
682:of
2097::
602:.
577:.
461:.
417:,
290:.
1742:e
1735:t
1728:v
672:e
665:t
658:v
613:.
588:.
552:.
480:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
