by Elizabeth S Paynter – CART Lab Director
There are many characteristics that help categorize a projectile point and identify what time period it was created. Projectile points are in part defined by their shape, specifically looking at the shape of the base, blade edge, basal edge and cross section. It is good to keep in mind, as with most things archaeological, that different groups may use different terminology to describe the same thing and that the nomenclature and identifying attributes may differ slightly.
Basic Point Shape
Some basic base shapes used to help classify a point include Bifurcate, Lanceolate, Notched, Pentagonal, Stemmed and Triangle. Pervious blog posts have covered descriptions for some of these shape types such as Corner Notched and Side Notched and Triangle Points.
More recently, CART has excavated a stemmed projectile point (pictured above). Stemmed points can be identified in several ways such as Straight, Expanding or Contracting. A straight stem has somewhat parallel sides. An expanding stem widens at the base. A contracting stem converges towards the base.
Descriptions for the basal edge include flat, concave, convex, and oblique. A flat basal edge has a fairly straight proximal edge of the base. A concave basal edge is a base that indents. A convex basal edge protrudes. An oblique basal edge exhibits angles that are acute and obtuse.
The blade edge is yet another helpful tool in typing a projectile point. Straight blade edges do not curve. Excurvate edges bulge out in a smooth convex curve. Incurvate edges indent in a smooth convex curve.
Cross Section Shape
If a projectile point is cut across the blade horizontally, the shape of the cross section varies. Cross section shapes often include biconvex, median ridged, plano-convex, and flat cross section. A biconvex cross section protrudes out on both faces in a convex curve making an elliptical shape. Median ridged is diamond shaped. Plano-convex is somewhat flat on one face and protrudes outward in a smooth curve on the other side. A flat cross section is flattened on both faces of the projectile point.
The projectile point pictured at the beginning of this post is broken at the top exhibiting its biconvex cross section.
Read Let’s Get to the Point about Typologies to understand why identifying the projectile point type is important.
MAC Lab. 2012. Diagnostic Artifacts in Maryland. Maryland Archaeological Conservation Lab (MAAC Lab). Originally Published 2002. Electronic. http://www.jefpat.org/diagnostic/index.htm accessed February 21, 2018
VDHR Collections. Native American Comparative Collections. Virginia Department of Historic Resources. Electronic. http://www.dhr.virginia.gov/arch_DHR/archaeo_lpc.htm accessed February 21, 2018