The Jack's Reef Horizon: its arrival and distribution during the Late Woodland period in Illinois

The introduction of Jack's Reef cluster points in Illinois occurred against a backdrop of complex social relationships and technological change. The Late Woodland period, circa cal A.D. 650, was a dynamic time. This is particularly apparent in the archaeological record of the west-central part of the state. Technological innovations, such as the appearance of semi-subterranean structures, globular jars and in the American Bottom, bowls, and the bow and arrow emerged "overnight" in what we view to be a frontier or shatter zone, aplace where social and technological interaction was vibrant. The earliest use of Jack's Reef cluster points as secondary or coeval styles and the birth of the Sponemann identity in the American Bottom coincide with these innovations. The earliest documented Sponemann occupations, derived from an interaction between local American Bottom Patrick populations and Fall Creek people from further north in the Sny Bottom of the Mississippi River trench, were located at the north end of the American Bottom. The use of Jack's Reef cluster points in this area was brief, but it endured long enough to become a marker for the period cal A.D. 650-700 in the northern American Bottom. Jack's Reef cluster points occur as minority styles across much of Illinois and in many areas, their intrusion appears to have occurred later in the local sequence than cal A.D. 700. Their distribution in the state is uneven and in some places they do not occur at all. This paper outlines what we currently know about the arrival and distribution of Jack's Reef cluster points in Illinois, and we examine possible associations with social and technological changes. In doing this, we focus on the ethnogenesis of the Sponemann identity in west-central Illinois.