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What is Thin Sectioning?

Thin-sectioning (also known as, thin-section analysis) is an important technique used in Archaeology for the examination of the composition of various materials. Typically, such materials include ceramics or stone.

Thin-sectioning is the removal of a very thin piece (roughly 0.03 mm) of material from the object in order to be observed under a microscope. The sample needs to be so thin that the details of the material (small internal structures, and crystals) are readily displayed in the microscope in order to undergo proper analysis. This method is crucial in determining the raw material used for the specific object, or in the case of faunal remains, determining how the animal was killed. While we are able to obtain crucial information from thin-sectioning, it has some limitations. For instance, thin-sectioning is an abrasive method which doesn’t align with the archaeological view of limiting destructive analysis techniques on artifacts.

 

Thin sectioning is only done on samples with no accompanying context. Here samples are first coated with epoxy to create pucks that are later cut to a thickness of 30 microns.

 

Thin-sectioning is a core method in petrology, or petrographic analysis, which is the identification of mineral composition and texture of the material, such as rocks and ceramics. Such technique is not limited solely to ceramics or stone, but applied to soil, plant, or bone remains. Petrographic analysis can be used in many diverse areas of study. For example, Gregory V. Braun from the Department of Anthropology in the University of Toronto, used petrography to investigate Iroquoian ceramic production and smoking rituals in a middle Ontario Iroquoian village near southern Ontario. For those interested, the link to his publication is in the reference section below.

 

Thin-section samples from Sustainable Archaeology: McMaster in varying states of progression.

Both images are sourced from Sustainable Archaeology: McMaster. July 29th, 2015. http://www.dayofarchaeology.com/sustainable-archaeology-mcmaster/

References

Biittner, Katie M. and Susan M. Jamieson. Chert Raw Material Utilization at the Bark Site (BbGp-12), Peterborough County, Southern Ontario (2006). Ontario Archaeology 81/82.

Braun, Gregory V. Petrography as a technique for investigating Iroquoian ceramic production and smoking rituals (2002). Journal of Archaeological Science 39, 1-10.

Day of Archaeology. “Sustainable Archaeology McMaster: A Day in the Life of an Archaeological Repository.” Published July 29th, 2015. http://www.dayofarchaeology.com/sustainable-archaeology-mcmaster/

Archaeology Wordsmith. “Thin-Sectioning.”Accessed April 4th, 2018. http://www.dayofarchaeology.com/sustainable-archaeology-mcmaster/

ROM Collections and Research. “Ceramic Petrology Laboratory.” Accessed April 4th, 2018. https://www.rom.on.ca/en/collections-research/research/world-culture/ceramic-petrology-facility

A Look Back: An Unusual Holcombe Point in the Vogt Collection

Originally from the Palisade Post, 1987 Vol 9 no.1

The museum received a donation of artifacts from the Vogt family, obtained from Lambton County. One of the artifacts in this collection is an unusual “Holcombe” point.

Drawing made for the museum by artist Catherine Comrie.

The Holcombe point type was first defined on the basis of specimens recovered on Holcombe Beach in Macomb County Michigan. Often made from Onondaga or Bayport Chert, this lanceolate point with a concave base and fine parallel flaking is confined to the later part of the Paleo Period ca.8000 BCE.

Holcombe points are always quite thin, have lateral edge grinding, and are rarely fluted. Although rare in Southern Ontario, at least one site with predominantly Holcombe points has been documented in the area.

This point classified as Holcombe is made from Flint Ridge Chert, which outcrops in Ohio. According to knowledgeable researchers, very few Holcombe points are made of this material.

At first glance, this point appears to be uni-facially fluted (ie. similar to fluted points). Close examination reveals that a large flake was removed during the preform stage, and that it is not a flute but rather a scar from a large flake removed from the tip. The concave base has been heavily retouched but is not ground.

Based on size alone, this point is much larger than typical Holcombe points measuring at 5.7cm in length. As with the specimens found at Holcombe beach, it is possible this point finished it’s life as a hafted knife.