Paleo-Indian
The Paleo-Indian period in North America dates to about 9,500-7,500 B.C. Paleo-Indians in Iowa encountered vastly different environments than those of the recent past. The climate was cooler and wetter than present averages. In north central Iowa, Paleo-Indians lived in recently deglaciated landscapes covered by boreal and conifer-hardwood forests, shifting through time to elm- and oak- dominated woodlands. Woodlands predominated in most of the state as well, and prairie, if present, was very limited.

The Clovis complex is the earliest well defined archaeological culture currently known in North America. Clovis and other fluted projectile point styles were made during the first two-thirds of the Paleo-Indian period, and Dalton and unfluted point forms date to the latter one-third of the period. Aside from these lanceolate (lance-shaped) points, defining characteristics of the Paleo-Indian period include distinctive butchering tools, extensive use of exotic chert types, and specialized lithic technologies. Fluted and unfluted point forms have been recovered as surface finds from upland and valley locations throughout Iowa.

Paleo-Indian peoples were extremely mobile, hunting various animals including now-extinct large mammals such as mammoth, mastodon, and giant bison. Most Paleo-Indian sites so far located in the United States are large mammal kill sites, and little is known of other site types. No Paleo-Indian base camps have yet been documented in Iowa. To date, the best documented fluted point site in Iowa is a plow-disturbed cache of Clovis points known as the Rummells-Maske site in Cedar County.

Archaic
The Early Archaic period (7,500-5,500 B.C.) is viewed as a somewhat transitional period between cultures relying on big game for subsistence and those with a more rounded forager adaptation. Environments changed relatively quickly, as deciduous woodlands, mixed with prairies in western areas, became established over most of the state. Populations probably depended on bison in western Iowa and on deer and elk in eastern Iowa. These large mammals were supplemented by smaller game and by increasing use of plant foods. Settlement types included somewhat permanent base camps and seasonally occupied resource procurement camps. Excavated sites, such as the Cherokee Sewer site, suggest local populations were small and that they were tied to a seasonal round of resource exploitation. Representative artifacts include medium to large spear points, often with serrated and beveled blade edges.

The Middle Archaic period (5,500-2,500 B.C.) is so poorly known in Iowa that it has normally been lumped with the Early Archaic. Cultural adaptations may have been similar, but environmental conditions became increasingly arid throughout the period. The Middle Archaic period corresponds to the warmest and driest postglacial period, commonly referred to as the Atlantic episode, or the Hypsithermal. Human populations throughout the Midwest gravitated to the wetter river valleys, and because of this, Middle Archaic sites are often deeply buried and difficult to locate. During the Hypsithermal, great masses of silt filled river valleys, and alluvial fan development was rapid. Many Middle Archaic sites are buried in these alluvial sediments.

By the Late Archaic period (2,500-500 B.C.) the Midwest was becoming a fairly crowded place with the incidence of intergroup encounter rising sharply. This situation resulted in similar subsistence strategies over broad areas, but also in increased territoriality, local differentiation in artifact styles, and development of intergroup trading networks. The end of the dry Hypsithermal resulted in increased stability of the resource base and made many previously unsuitable areas attractive for settlement. Population levels appear to have increased substantially, and a somewhat sedentary life way as well as construction of large ossuaries (multiple-interment cemeteries) are documented for this period. The use of communal cemeteries reinforces the interpretation that populations were becoming more sedentary.

Woodland

The Woodland tradition (500 B.C.-A.D. 1000) was characterized by improved technologies, such as ceramic production and horticulture, leading to an overall increase in productive efficiency, and by the construction of burial mounds. Although these characteristics originated during the Archaic, only after 500 B.C. did they come together and become adopted over a wide area.

Woodland peoples refined their hunter-gatherer adaptations, making heavy use of fish and clams in major river valleys, and continuing to exploit deer and bison. Dependence on cultivated plants increased. Native plants often thought of as weeds today were grown for their nutritious seeds. Woodland farmers developed domesticated varieties of some of these native grain crops long before corn or beans became important. Climatic conditions approached modern averages, landform development stabilized in most places except in flood plains and stream channels, and vegetation patterns were much like the forest-prairie mix documented by nineteenth-century land surveys.

Early Woodland settlements (500-100 B.C.) in the Midwest were small and seasonally occupied. Early Woodland subsistence patterns in Iowa are not well known, but they probably involved broad-based procurement of mammals, birds, and aquatic species. Early Woodland peoples built large burial mounds similar to some in Ohio, and they interacted with groups throughout the Midwest, as evidenced by artifacts made of exotic raw materials. The typical Early Woodland spear point was a straight stemmed or contracting stemmed point, and pottery of the period includes both a thick, flat- bottomed type (500-300 B.C.) and a thinner, bag-shaped type often decorated with incised lines in geometric patterns (300-100 B.C.). Early Woodland sites are relatively common in the Mississippi Valley but are difficult to identify in central and western Iowa. Perhaps groups on the eastern Great Plains retained an Archaic lifestyle during this period.

The Middle Woodland period (100 B.C.-A.D. 300) is noted for its refined artworks, complex mortuary program, and extensive trade networks. Middle Woodland communities throughout the Midwest were linked by a network archaeologists refer to as the Hopewell Interaction Sphere. Trading involved materials such as Knife River flint from North Dakota and obsidian from the Yellowstone Park area. Also exchanged through the Hopewell network were artifacts of marine shell, copper, mica, and several pipestones, as well as high quality ceramic vessels and possibly perishable materials which have not survived archaeologically.

By Late Woodland times (A.D. 300-1000) the continent-wide exchange of exotic goods declined but interaction between communities and tribes continued. Population levels apparently increased rapidly. In some parts of Iowa, Late Woodland peoples aggregated into large, planned villages, but in most of the state settlements continued to be small and generally became more dispersed across the landscape. Uplands and small interior valleys became settled or more heavily utilized. Late Woodland peoples introduced the bow and arrow into the Midwest. Continued native crop horticulture and diversified hunting and gathering provided the subsistence base through most of the period. Corn was introduced to many groups after around A.D. 800 but did not form a staple crop until the Late Prehistoric period.

During the Late Prehistoric period the Oneota culture dominated much of eastern Iowa as well as extensive parts of central and northwestern Iowa. Oneota peoples lived throughout the Midwest between around A.D. 1050 and 1700.

The Plains Village pattern appeared in Late Prehistoric times (A.D. 1000-1650)