Geoarchaeology Class 3/9/2011

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The Geoarchaeology class had two assignments from last week:

1) Updating and validating plan view maps from the previous excavation efforts of the Folsom wedge in 2009.

Once the plan views were updated and the initial identifications made, a preparatory cleaning of the bison bone and matrix was conducted to prepare for removal of the stabilized bone.

2) Beginning the granulometric analysis from auger tests at LA3324 Locality X.

The granulometric analysis refers to the measurement of sediment grains with regard to the distribution of particle sizes in a sample.  Particle size distribution aids the interpretation of conditions under which sediments were deposited, including the strength and variability of the transport agent (Kilby 2011).

Students prepared sediment samples by first removing extraneous particles, disaggregating consolidated sediments, then size grading through a nested set of sieves.  Most of the size grading work was performed by the mechanized Ro-Tap shaker.  Once the individual levels of sediment were size graded and weighed, a microscopic analysis of each size class was conducted to record observations of texture, sphericity, organics, and micro-artifacts.

Artifact of the Week 3/7/2011

LA3324.24177: Modified bone.

This bone tool was was discovered by F. E. Green in 1963 during the Blackwater Draw North Bank excavations.  This tool is made from a portion of bison scapula or shoulder blade.  The scapula is used for making numerous tools but may be most recognizable on the Great Plains in the form of a scapula hoe used for gardening.

To learn more about scapula hoes and many other bone tools, visit Bone Tools.

Artifact of the Week 2/28/2011

LA3324.32904: Unfluted Folsom projectile point fragment made of Alibates agate.

This artifact was excavated from the Blackwater Draw North Bank in 1963 by J. Collins.  This fragment was found in the Folsom-age horizon just 36 cm (14 inches) below the Agate Basin stratigraphic unit.

Alibates chert, sometimes called “flint”, is better described as an agatized dolomite.  The Alibates Flint Quarries located near Amarillo, TX is the source for this raw material.

To learn more about this commonly used raw material, visit Alibates Flint Quarries National Monument.

Still work to do

Its been quite a while since I posted anything here but work goes on despite the cool weather.  We are working in the South Bank Bison kill repairing and preserving in situ bones from the Late Paleo/Early Archaic strata.

Bone Stabilization

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With the 46 year-old plaster removed the only real damage visible is the extreme drying of the entire block.  The bone is substantially softer than the surrounding matrix and has suffered from shrinkage of the sediment.  The block is regularly misted with distilled water and a humidifier runs almost constantly in the WeatherPort.  As may be seen in the above photo, the bones were partially excavated prior to jacketing and at least one was removed prior to closing the block as evinced by a negative imprint in the sediment.  Also visible in the block are crumbles of sediment, bone, and plaster which will need to be removed.  There is evidence, especially in low areas that some substance, probably white glue was applied to the block.

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The block was divided into quarters for excavation.  The near side will be removed while the far side will be preserved, revealing a profile of the bone-bed.

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Heather Davis (above) is removing crumbled sediment and unassociated bone fragments from one quadrant while sealing and preserving the in situ bone.

There are essentially two interconnected projects happening with the block.  The Site Archaeologist and assistants are working to maintain the integrity of the bone and associated artifacts while the Advanced Geoarchaeology class maps and excavates half the block and studies the sediments in order to gather geologic and environmental data.

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George Crawford re-fitting and treating exposed bone with Heather Davis.  Photo by Garrett Kubik.