Archaeology of Iowa

The oldest artifacts found in Iowa are Clovis points, large lanceolate points found occasionally in all parts of the state except for the Des Moines Lobe. Possible sources of game were giant Pleistocene megafauna, including mammoth, mastodon, and giant forms of bison, all of which are now extinct. While widespread, only two Clovis sites have been excavated in Iowa. The Rummells-Maske site is a Clovis site in Cedar County; unfortunately, this site was damaged by plowing, although 20 points and point fragments were recovered.[7] The Carlisle Clovis Cache Site in Warren County contained 38 unfinished stone tools that appear to date to the Clovis period, but these results have not yet been published.[8]

Other Iowa Early Paleoindian points include Gainey, a point that appears to be intermediate between Clovis and Folsom. Gainey points were also recovered at Rummells-Maske. While Folsom points are found throughout Iowa, especially western Iowa, none have been excavated in a well-preserved site.[9]

At the beginning of the glacial-free Holocene Epoch, humans in Iowa utilized projectile point found throughout the mid-continent, including Dalton, Fayette, Agate Basin, and Hell Gap. Humans were still highly mobile, and by this time most of the Pleistocene megafauna had gone extinct. As with the Early Paleoindian period, no intact Late Paleoindian sites have been excavated in Iowa.[10]

During the Early Archaic period regional variation in point forms is seen in Iowa, and Indians adapted to more localized forms of hunting and gathering while probably maintaining seasonal movements from camp to camp.[1] Common stone tool types are Corner-notched St. Charles points and Thebes Knives. Soon Hardin and Kirk points appear in Iowa as well.[11] Excavated Early Archaic sites in Iowa include the Soldow Site,[12] Horizons IIIa and II of the Cherokee Sewer Site,[1][13] and the Simonsen Site.[14]

Temperatures rose in the mid-continent during the Middle Archaic, a warming trend known as the Hypsithermal. Grasslands expanded east, forests became less common, and many Iowa lakes shrank or disappeared. Humans responded by diversifying their subsistence strategy: eastern Iowa saw a shift towards river resources, and western Iowa towards Plains resources. Excavated sites in eastern and central Iowa include the Brash Site,[15] the Gast Spring Site,[1] and the Ed’s Meadow Site.[16] Western Iowa sites include the Turin Site,[17] Horizon I of the Cherokee Sewer Site,[13] and the Pony Creek Site.[18]

In the Late Archaic the climate became more similar to modern with the end of the Hypsithermal. The number of Late Archaic Sites increased in Iowa, perhaps reflective of increased populations allowed by climate change and new subsistence strategies. The Late Archaic sees the first indication of mound building in Iowa, as well as direct evidence of domesticated plants, and large, long-term settlements. The Red Ocher Culture appeared in northeast Iowa, associated with copper artifacts and mound building. Numerous Late Archaic sites have been excavated in eastern Iowa, some showing the gradual adaptation of cultigens, including squash, little barley, marsh elder, and barnyard grass.[19] Sites with evidence for early cultigens in Iowa include the Edgewater Park Site in Coralville,[20] the Gast Spring Site,[1][21] and the Sand Run Slough West Site.[22] In western Iowa, Late Archaic sites are common, however large bison killing or processing sites are less common than before, and there is little evidence for the use of domesticated plants.[23]

The Early Woodland period saw the introduction of ceramics to Iowa, including Marion Thick and Black Sand types. Marion Thick may have originated with the nucleated Late Archaic cultures of the Upper Midwest, and was widespread in distribution.[24] Early Woodland Indians in eastern Iowa built large burial mounds in the Mississippi River region, and participated in long-distance trade of exotic raw material. This long-distance trade may have been the forerunner of the later Havanna-Hopewell trading sphere. In north-central Iowa, Early Woodland peoples appear to have interacted more directly with the Prairie Lakes region of Minnesota. Numerous Early Woodland sites have been excavated in Iowa, including the Gast Spring Site,[1] and many sites which have not been formally published.[25]

The Middle Woodland Indians of eastern Iowa participated at the edge of the Havana and Hopewell interaction networks. This cultural connection to the East is seen in the construction of large mounds, earthworks, and the trade of exotic goods over very long distances. There were several large earthwork enclosures in Iowa along the Mississippi that date to the Middle Woodland period, but none in the interior of the state, indicating Iowa is the western edge of Havana-Hopewell influence.[26] The Toolesboro Mound Group in Louisa County included a large octagonal earthen enclosure that covered several acres; earthworks of this style are indicative of the monumental construction once seen in Havana, Illinois along the Illinois River and sites in the Ohio River drainage including Chillicothe and Newark, Ohio. Hopewell trading networks were quite extensive, with obsidian from the Yellowstone area, copper from Lake Superior, and shells from the Gulf Coast appearing in Middle Woodland Iowa sites. Sites in eastern Iowa appeared to nucleate, vacating much of the hinterlands.[27] Western Iowa appears to have been not directly involved in this exchange network, and the Havana-Hopewell flourishing did not extend much above the Kansas City area of the Missouri River.[28]

The Late Woodland Period was once considered to be relatively unimportant and uninteresting compared to earlier and later periods, but recent research shows unexpected cultural complexity.[1][29] Late Woodland sites are more dispersed than Middle Woodland sites, but they are apparently more numerous. Gone are the complex earthworks and long-distance trade networks, but this does not appear to be a cultural collapse, since Late Woodland sites and artifact types overlap with and transition from Middle Woodland sites. Technical changes of the Late Woodland include the use of true arrow heads, thinner and larger ceramics with less elaborate decorations, and the adaptation of new crops, including maize.[30] Numerous regional variations and phases have been defined in Iowa, based in large extent on differences of ceramic form and decoration.[1] Excavations at Late Woodland sites are common, some of these sites showing surprising complexity. The Gast Farm Site excavations revealed a complex settlement associated with a midden of refuse 100 m in diameter. Large storage and food processing pits, trash middens, and other features were excavated. Occupants utilized acorns, other nuts and fruits, goosefoot, little barley, maygrass, sunflower, fish, birds, deer, muskrat, and turtle. There was little evidence of long-distance trade.[31] The Rainbow and M.A.D. sites provide a glimpse into the Late Archaic of western Iowa. At Rainbow, a large house was excavated, showing evidence of reuse and possible joint occupation by two families.[32] Mound building became more common during the Late Woodland Period, large groups of mounds appeared including the Slinde Mound Group, and the Fish Farm Mound Group.

The Late Woodland in Iowa is perhaps best known for effigy mounds, large, low mounds shaped like animals such as birds and bears. Effigy mounds are distributed across southern Wisconsin, northern Illinois, and northeast Iowa. A large concentration of mounds in several groups is preserved at Effigy Mounds National Monument. Like most mounds in Iowa, excavation reveals that these mounds were commonly used as sacred burial locations but contain few artifacts.[33] Recent ground-penetrating radar survey of selected mounds at Effigy Mounds National Monument reveal that many are badly disturbed, but others appear to be comparatively intact.[34] The Folkert Mound Group in central Iowa contains an enigmatic cruciform mound that may or may not be astronomically aligned.[35][36]

Great Oasis sites appeared in the Missouri River drainage, and have attributes of both Late Woodland and Late Prehistoric cultures. Great Oasis cultures extended through the eastern Plains from Iowa to South Dakota. Developing independently from the eastern Mississippian cultures, Great Oasis sites display large sites along major stream terraces, increased reliance on agriculture combined with hunting and gathering, substantial pit earth lodges, and a transition from Late Woodland to Late Prehistoric ceramic forms. Overall, Great Oasis appears to have been a regional adaptation of new forms of farming and settlement patterns, including seasonal occupation of different ecological zones, that includes aspects of Late Woodland and the subsequent Middle Missouri Tradition.[1][39][40]

Reconstructed Glenwood earthlodge, Glenwood, Iowa

In northwestern Iowa, Great Oasis underwent dramatic changes as Mill Creek sites appeared. While Mill Creek has many stylistic similarities with Great Oasis and some Mill Creek sites contain Great Oasis ceramic forms, Mill Creek sites are substantially different. Mill Creek sites became nucleated, often fortified, had a much higher dependence on maize and bison hunting, show substantial evidence of long-distance trade, and appear to have been occupied year-round. The Phipps and Chan-Ya-Ta sites are classic examples. Glenwood culture sites in southwest Iowa near the Missouri River appear to be unrelated to the earlier Great Oasis sites, and are notable for their large earthlodge sites. Glenwood sites appear to have been more oriented in lifeways and trade with the Central Plains Tradition cultures to the west than with the Mississippian cultures to the southeast. Around 1300 AD Mill Creek and Glenwood sites in Iowa disappeared, replaced by the rapidly spreading Oneota cultures.[41][42][43][44][45]

Excavation of the Oneota component of the Birds Run Site in Des Moines

Very large Mississippian centers appeared around AD 1000, with enormous earthen pyramids, palisades, and extreme social hierarchy. The earliest large Mississippian center was Cahokia, east of St. Louis. Cahokia appears to have dominated trade in the upper Mississippi, with satellite or closely aligned settlements as far as Aztalan in Wisconsin.[1][46] In Iowa, there is little evidence of Mississippian occupation, and the Late Woodland lasts longer in the east than in the west. This is puzzling, given the proximity to Mississippian cultures; it is possible that the nearby presence of the large, hierarchal Mississippian trading network inhibited local development.[1] After the decline of the Cahokia network after AD 1250 the local Late Woodland populations expanded in complexity, developing large nucleated villages and their own trading network, known as Upper Mississippian Oneota. Oneota, named by Charles Keyes for a river in northeast Iowa, was a large cultural manifestation that covered the Upper Midwest at the edge of the Mississippian cultures. Oneota sites are easily identifiable by the globular, shell-tempered pots, which typically have strap handles and incised designs. Pots of this kind were well designed for the cooking of porridge and foods made from the various cultivated foods of the area. Important Oneota sites in Iowa include Kingston,[47] Mckinney,[48] Christenson,[49] Blood Run,[50] Hartley Fort, the Lane Enclosure,[51] three sites in downtown Des Moines,[52][53] and sites along the Upper Iowa River, including several large earthwork enclosures.[26][54] After the decline of the Mill Creek and Glenwood cultures in western Iowa, Oneota cultures appeared across the state. It is widely accepted that the Oneota were the ancestors of modern American Indian tribes associated with Iowa, including the Ioway, Ho-Chunk (Winnebago), Otoe, Missouria, and Omaha.[1]