GEOARCHAEOLOGY and ARCHAEOPETROLOGY

Cannon Microprobe can assist in the determination of provenience of pre-historic stone artifacts by use of electron microprobe and scanning electron microscopy. 

The analysis of 2 mm polished windows created in stone artifacts allows the acquisition of back scattered electron images which show micro-mineralogical texture and allow the acquisition of high quality x--ray spectra of individual mineral grains. Such data, when compared to a library of similarly analyzed rocks from suspected source areas can furnish definitive determination of the source of a stone artifact. 

The following x-ray spectra and back scattered electron images represent a case history in which a Washington State Olcott point with a 2 mm polished window has been compared to a small library of data for vitrophyric dacite reference materials.  For comparison purposes, please note the potassium / calcium peak ratios, sodium peak heights and titanium peak heights in the spectra.  The "Cache Creek 7" reference sample contains an unusual chromium rich titanomagnetite.  Observation of such a mineral phase in a stone tool would almost certainly demonstrate an affiliation with a particular quarry source. 

The vitrophyric dacite reference samples were collected by Dr. Edward F. Bakewell and are fully described in his University of Washington PhD thesis published in 2005.  The title of the thesis is "The Archaeopetrology of Vitrophyric Toolstones, With Application to Archaeology in the Pacific Northwest"  It is Bakewell's theory that most of the early stone tools in the Northwest USA were fashioned from a very few quarry sites rather than from countless opportunistic localities.  It is also his theory that most tools which have in the past been described as "basalt", are, in fact, vitrophyric dacites. 

The bottom of this page shows the x-ray spectra for two Olcott points in the collection of the Smithsonian Institution.  One of them compares very well to the analysis of the Lindell Point.

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The Lindell Columbia River Olcott Point showing its 2 mm polished analysis window.

BACK SCATTERED ELECTRON SCANNING ELECTRON MICROSCOPE IMAGES 

POLISHED SECTIONS OF LINDELL OLCOTT POINT AND FIVE VITROPHYRIC DACITE POTENTIAL SOURCE ROCKS

Lindell Olcott Point                         Stockhoff Vitorphyre  #4 - 03     Cache Creek Vitrophyre #7 - 02

Cache Cr.  Vitrophyre #9 - 02       Watt's Point Vitrophyre #1 - 03   Watt's Point Vitrophyre #3 - 01

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X-RAY SPECTRA OF SOME OLCOTT POINTS AND THEIR POTENTIAL DACITE SOURCE ROCKS

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Lindell Olcott Point  collected 1962, 1 mile above Columbia River along Abernathy Creek, Cowlitz County, Washington.  West of Kelso.

X-Ray Spectra of Lindell Olcott Point

Bulk x-ray spectrum of Lindell Point

Bulk x-ray spectrum of glass matrix of Lindell Point

X-ray spectrum of pyroxene phenocrysts in Lindell Point

X-ray spectrum of titanomagnetite crystals in Lindell Point

CC7 = Cache Creek British Columbia vitrophyric dacite 

Bulk X-ray spectrum of Cache Creek 7 vitrophyric dacite

X-Ray spectrum of  Cache Creek glass or matrix

X-Ray spectrum of Cache Creek 7 pyroxene.

X-Ray Spectrum of Cache Creek 7 titanomagnetite

CC9 =  Cache Creek British Columbia vitrophyric dacite

Bulk X-Ray Spectrum of Cache Creek vitrophyric dacite

X-ray spectrum of Cache Creek 9 glass

X-ray spectrum of Cache Creek 9 pyroxene

X-ray spectrum of Cache Creek 9  titanomagnetite

CWP # 1 Watts Point British Columbia Vitrophyric Dacite

Bulk X-Ray Spectrum of Watts Point # 1 vitrophyric Dacite

X-Ray Spectrum of Watts Point # 1 glass

X-Ray Spectrum of Watts Point # 1 titanomagnetite

X-Ray Spectrum of Watts Point # 1 pyroxene

CWP # 3 WATTS POINT British Columbia vitrophyric dacite

Bulk X-Ray Spectrum of Watts Point vitrophyric dacite

X-Ray Spectrum of Watts Point vitrophyric dacite glass

X-Ray Spectrum of Watts Point vitrophyric dacite pyroxene

X-Ray Spectrum of Watts Point vitrophyric dacite titanomagnetite

ST-4  STOCKHOFF Washington VITROPHYRIC DACITE

Bulk X-Ray Spectrum of Stockhoff vitrophyric dacite

X-Ray Spectrum of Stockhoff vitrophyric dacite glass

X-Ray Spectrum of Stockhoff vitrophyric dacite pyroxene

X-Ray Spectrum of Stockhoff vitrophyric titanomagnetite

OLCOTT POINT,  Washington State, Smithsonian # 340066

Bulk X-Ray Spectrum, Raw Surface

OLCOTT POINT, Washington State, Smithsonian # 416826

Bulk X-Ray Spectrum, Raw Surface