This chert Angostura point is from Yuma County, Colorado.  It was collected from the Slim Arrow site.  Angostura points date to the Late Paleoindian period, ca.  7500-10,000 BP.

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This point was collected by Perry and Harold Andersen sometime between 1927 and 1934 from the Slim Arrow site in the Wray dune field, between the Arikaree and North Fork of the Republican River in Yuma County, northeastern Colorado.  The dustbowl conditions that prevailed during that period uncovered previously-unknown sites for collectors like the Andersens, and their finds stimulated subsequent archaeological work that defined the Paleoindian chronology for the Great Plains of North America.  This point is among the finest examples of transverse parallel pressure flaking world-wide.  The point was made from Niobrara chert which outcrops about 225 km east of the Slim Arrow site.

This point was once in the private collection of the art and antiquities dealer Forrest Fenn, who died in 2020.  It has reportedly been bought by another collector.  The point is photographed as part of the University of Nebraska State Museum, Anderson Collection, Slim Arrow Site (V4).

The model was made of an epoxy cast from lithiccastinglab.com.

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Angostura points from northeastern Colorado are part of the Late Paleoindian Plano period.  During this period, hunting continued to focus on bisons, and on the Great Plains mass-kill sites have been discovered where bison have been cornered in traps in gullies and killed, or driven over cliffs.  Among the most famous of these is the Olsen-Chubbuck site in Colorado, where 190 bison were killed with spears or darts in ca. 10,200 BP.  Near the Rocky Mountains, people during this period practiced what the famous archaeologist George Frison called the foothill-mountain adaptation, which involved shifting between exploitation of bison on the plains and elk and mountain sheep at high elevations.  Points during this period were stylistically variable, with various types overlapping in time and grading into each other morphologically.  The Angostura style is one such type, with a great deal of variation in point size and workmanship, although most were finished with transverse-parallel pressure flaking.  Angostura points, broadly defined, are found across much of the middle portion of the United States, centred on the Great Plains, but the finely-worked specimens like this model are confined to the western Great Plains and eastern front of the Rocky Mountains.  This variety was originally called ‘Oblique Yuma’ in the 1930s, but the Yuma designation in ensuing decades became a broad catchall category.  It has since been subdivided into separate types (such as Angostura, Eden, Scottsbluff, Agate Basin, and Hell Gap), and archaeologists rarely use the term Yuma to describe points from this period.

The pressure flaking methods used on Plano period points included expertly-controlled oblique transverse-parallel techniques as well as right-angle collateral techniques, and, on the best-made examples, the workmanship ranks among the most skilled examples of pressure flaking world-wide.  Of particular note is the collateral pressure flake scars on Eden points that terminate precisely at the mid-point of the biface, creating an exceptionally prominent and precise ridge down the centre of both faces and a diamond-shaped cross section.  Modern flintknappers achieve this effect by using a slotted block under the biface held in the hand, with each flake removed over the space afforded by the slot.  Since the face of the stone is unsupported in that location, the crack ends in a feather termination at the biface’s midline.  It is also possible that the Native Americans who made these points used a holding system that did not require a slotted block.  For instance, Aboriginal flintknappers in the Kimberley region of Australia achieve a similar effect by holding the point edge-on on an anvil placed in front of them.  On other points from the Plano period, such as the Angostura point, the transverse-parallel pressure flakes ‘roll over’ the midline of the biface and terminate near the opposite edge.  This implies that the face of the biface was supported in some way.