How Archaeologists Know the Age of Artifacts - Arrowheads & Typologies
Clovis Points originating from locations across North America (taken from Eren et al. 2020)
It’s the first question archaeologists ask… How old is it?
It is of the utmost importance for an archaeologist to understand the age of any particular artifact. After all, without knowing the timing it is impossible to place an archaeological item or site in its proper context. So, the question follows: how do we know the age of artifacts (and sites)? This article begins to answer that by focusing on one piece of the puzzle: projectile points, or as they are more commonly known, arrowheads.
Although a thorough discussion of stone projectile points (what they are, how they were made, and how they were used) is beyond the scope of this blog, let’s go over some basics (we recommend Andrefsky 1998 and Justice 2002 for more details). They are created through a process called knapping, which consists of striking a piece of stone that has the right qualities (e.g., flint/chert, obsidian, fine-grained basalt) with a harder stone in order to remove pieces to create a desired shape. A projectile point is typically fixed to the end of an arrow or dart shaft, which can then be shot/thrown. While projectile points can come in a variety of shapes and sizes, they typically have some combination of the following features (refer to the photo above): a base; a stem and/or notches; a blade; a body; a shoulder (if stemmed); a tip. Some less common features include serration and fluting (see the photo above for examples of fluted points).
There is a long list of methods archaeologists use to determine dates, all with varying approaches and degrees of accuracy (Sutton and Arkush 2019 for an introduction to many of these methods). Absolute dating refers to methods which provide a numerical date range (e.g., radiocarbon dating, optically stimulated luminescence). Relative dating refers to methods which place archaeological material into sequences, showing which artifacts/sites are older, coeval, or younger when compared to others (e.g., stratigraphic sequencing). It is typological segregation, a relative dating method, which allows archaeologists to quickly determine the date range that a particular projectile point is associated with. This method involves sorting artifacts into distinct categories or “types” based usually on their overall shape. Types are particular to geographic regions and thousands of types have been developed for projectile points around the world.
When possible, a date or range of dates is determined for any given artifact/site when it is studied. This can involve any combination of absolute and/or relative methods depending on the conditions and available funding. By looking at dates associated with many specimens of a type, an age range is assigned to the type. Because this has been done so extensively, when a projectile point is found, it can usually be assigned to the date range associated with its type. A common source used to assist archaeologists working in our region to determine the correct type and its associated age is the book Stone Age Spear and Arrow Points of California and the Great Basin by Noel Justice (2002).
Let’s look at an example. BCR Consulting archaeologists found a projectile point during a survey of a project located in the western Mojave Desert between Barstow and Needles, California (see photo). The point had several distinct shape qualities which were most helpful in assigning it to a type. It had a stem which was wide and square with a concave base which was thinned near the end of the manufacturing process. The blade was excurvate (rounded outward). Based on these things and the overall shape, the point most closely matches the Stanislaus Broad Stem type, which is part of the Borax Lake Cluster. It’s date range spans from 6,700 to 6,200 years ago.
One of the most widely recognized projectile point types in the Americas is the Clovis Point (Justice 2002 and Waters et al. 2020 for details regarding this type). These artifacts were created between 13,050 and 12,750 years ago (cal BP) throughout most of the Americas. This was long before development of the bow and arrow in this part of the world and these points are therefore understood as dart points (larger and used for atlatl projectiles) rather than arrowheads. A hallmark quality of the Clovis Point is fluting. This is a longitudinal depression which runs up from the base of the point towards its tip, usually terminating between a third and halfway up the length of the item. The flute was created as one of the very last steps of the flintknapping process and it functioned to facilitate attaching the point to the dart shaft.
Stanislaus Broad Stem Arrowheads
A type of projectile point with a wide, triangular blade and a broad stem with a concave base, found in California's central coast and Sierra Nevada region. They are similar to the Stanly point but distinguished by their concave base.
There are, of course, plenty of caveats which need to be considered (Andrefsky 1998, Flenniken and Raymond 1986, and Flenniken and Wilke 1989 for more details). There are too many to cover here, but let’s touch on some important ones. Modern researchers have categorized projectile points into types based on various similarities. It is impossible to know if past people who made these items recognized the same division of categories. For example, some types are based on the perceived function of the tool (e.g. arrowhead, hide scraper, knife) while some are based solely on their shape. It is often very difficult or impossible to determine the function of an artifact with complete certainty. Furthermore, the list of specimens included within any given type would change if the qualities that define the type (e.g., overall dimensions, presence of a stem, shape of the base) were shifted or their relative weight was altered. We usually have no way of being certain which qualities were recognized and meaningful to the creators.
Some archaeologists believe that the use of typological categories as indicators of date range is misleading. While the ranges assigned to types are rarely one hundred percent accurate and are often modified as more data is gathered, typologies remain a useful and common tool, even if there are important caveats. As long as we are aware of the limitations of typological categories, they can be employed successfully as part of the archaeologist’s extensive toolkit.
References
Andrefsky, William Jr
1998 Lithics: Macroscopic approaches to analysis. Cambridge University Press, Cambridge, UK.
Eren, Metin I., Brett Story, Alyssa Perrone, Michelle Bebber, Marcus Hamilton, Robert Walker, and Briggs Buchanan.
2020 North American Clovis Point Form and Performance: An Experimental Assessment of Penetration Depth. Lithic Technology 45(4):263-282.
Flenniken, J.J. and A.W. Raymond
1986 Morphological Projectile Point Typology: Replication, Experimentation, and Technological Analysis. American Antiquity 51.
Flenniken, J.J. and Philip J. Wilke
1989 Typology, Technology, and Chronology of Great Basin Dart Points. American Anthropologist 91.
Justice, Noel D.
2002 Stone Age Spear and Arrow Points of California and the Great Basin. Indiana Universtiy Press, Bloomington, Indiana.
Sutton, Mark Q., and Brooke S. Arkush
2019 Archaeological Laboratory Methods: An Introduction. 7ᵗʰ ed. Kendall Hunt Publishing Company, Dubuque, Iowa.
Texas State University
2025 Understanding Projectile Point Typology. Electronic document, https://www.springlakearchaeology.txst.edu/sldr2014/artifacts/lithics/sldrppoints/typology.html, accessed 10/30/25.
Waters, Michael R., Thomas W. Stafford Jr., and David L. Carlson
2020 The age of Clovis –13,050 to 12,750 cal yr B.P. Science Advances 6(43).
