Thursday, October 15, 2009

Jasper Gouge, Sebasticook River, Winslow, Maine.


This rock doesn't look like much else than a rock.

Turned this way, it looks a little more suspect, but not too much.

But held properly in the hand, it is a perfectly fit hand gouge.

From the bottom and side, a crafted, curved blade surface becomes apparent.


This artifact has a funny story. Last Sunday, my brother Tim and I were looking over a Ceramic Period habitation and possible pottery kiln site on the lower Sebasticook River in Winslow, Maine. I found the rock above on the ground, in an area with numerous worked flint flakes, and because it was jasper with bright red flecks (which is uncommon on the Sebasticook), I pocketed it for our rock garden.

Later that Sunday night, I absentmindedly picked up the rock while we were all playing a board game and noticed how perfectly it fit into my hand, and when held in this position an even, curved cutting surface was apparent at the end of the stone, much like a small hand plane for woodworking. I then did a Homer Simpson, "D'Oh !!!!" and realized I had found a prehistoric hand gouge and didn't even know it.

Now, having examined it more carefully, I am convinced it is a hand gouge and was specifically made for this use. What convinced me is not just the shape and its tailor-made fit for the hand, is that it is made out of jasper.

Among Maine geologists, red jasper is a generic term for an extremely hard, tough and dense rock that appears in highly polished cobbles in the bed of the Kennebec River and Androscoggin Rivers and their headwater tributaries. A key diagnostic for this jasper is the presence of deep maroon to blood red swirls and specks within a larger matrix of black, gray and tan.

Robert Doyle (2008) describes the Kennebec jasper variety as a "cryptocrystalline variety of chert, lacking any kind of internal structure. Color is dependent on the content and chemistry of included iron oxide impurities. Red jasper usually forms in association with iron ores, such as those from the Minnesota Iron Range, and occasionally as exhalative deposits of basalt flows ... No local outcrop source for this lithology has been identified. The boulders in the glacial drift are well rounded, suggesting a lengthy journey from the outcrop source. The jasper boulders at New Sharon (Maine) are dark blood red to rusty-red colored, containing black and gray swirling mottles and fracture fillings of dark quartz. Red jasper is very dense, extremely durable and hard."

Close-up of swirling texture in a large jasper cobble from a marine clay deposit along the Kennebec River in Augusta, Maine.

One reason this type of jasper is an uncommon prehistoric tool material is that it is extremely hard and difficult to work, even for skilled prehistoric blade and tool makers. Because it is only found in polished, highly waterworn cobbles, any piece of jasper that has angular, non-rounded edges strongly suggests somebody was actively working it.

Red jasper cobbles from the Kennebec River, Augusta, Maine. These are about the size of golf balls. Dipping the cobbles in water brings out their intense red coloration, which is why I found all these in the shallow parts of the Kennebec River.

A key diagnostic of our Sebasticook River piece of jasper is that about 80 percent of the piece is broken, with just a few remnants of the original, water worn surface of the cobble still showing. Despite this, the angular, worked faces of the jasper are subtle and could be easily mistaken for a river stone cracked and broken by frost action along zones of weakness or structural bedding.

This illustrates the importance of identifying the lithic materials used by prehistoric tool makers and understanding their geological origin and textural character. Because I know from experience that this type of red jasper is almost never found except in very smooth, water worn cobbles, finding a highly angular chunk of this stone is a strong suggestion that it was worked, even if the form is not complete. In contrast, one can be easily fooled by an apparently "worked" surface on bedded rocks like schist or slate when what you are really seeing is the rock naturally splitting along bedding planes from frost or water action. Most of central Maine is underlain by tightly bedded and folded slate and schist, which creates countless thousands of "artifact-looking" rocks that aren't. Even more confusing is that the dominant bedrock in central Maine is a gray phyllite slate, which in small pieces looks almost identical to the dominant prehistoric flint type, the Mt. Kineo-Traveler Mountain rhyolite.

Wetting the jasper gouge shows the diagnostic blood red specks and tendrils. This stone has much more quartz and is coarser than most red jasper cobbles in the Kennebec River valley, which undoubtedly made it easier to make into a gouge. Arrow points to the carefully worked cutting edge.


The area below the yellow arrows has been struck off from the original jasper cobble. The red arrows show two separate strikes to create the inclined plane of the gouge and a hand-holding surface.


The cutting edge of the gouge, viewed from the bottom. All of the surfaces have been created by striking the original waterworn cobble and shearing it off in the intended direction.

Top of gouge showing two parallel struck grooves. All of the surfaces shown here have been struck from the original cobble. Based on some testing, this surface may in fact be the bottom.

This gouge from the Sebasticook is enigmatic because it uses a locally available material, red jasper, that is extremely difficult to work into a usable tool, and for this reason is a lithic material used rarely by prehistoric Maine people. The rock itself is enigmatic because it is an uncommon, but fairly consistent constituent of the glacial rubble within which flows the Kennebec and Androscoggin Rivers and their headwater tributaries, yet nobody knows its actual bedrock source, which Bob Doyle surmises must have been somewhere in far northern Maine or southern Quebec.

Having walked and waded the headwaters of the Kennebec and Androscoggin Rivers for nearly 20 years, fishing for brook trout, panning for gold, swatting black flies, taking photos, and looking for a place to camp, these odd blood red pieces of jasper have been a constant, but uncommon, fixture of the landscape. Viewed in the crystal clear water of the Swift River in Byron, Maine or Nash Stream north of Rangeley Lake, or the Kennebec River in Vassalboro, these nuggets of red jasper leap out at your eye as you look into the water and demand your attention. I am sure they had the same effect on the people living in central Maine 2,000 years ago, who had a much more practical interest in stone than we do today.

I consider this jasper gouge an anomaly in two senses. One, jasper cobbles are extremely uncommon on the Sebasticook River and two, a prehistoric Maine person decided to go against all odds and make a wood plane out of one of them. This jasper is extremely hard to work because, unlike flint and chert, it does not want to break into flat planes and conchoidal surfaces. It either does not break at all or shatters into squarish pieces only if you beat the hell out it.
References Cited:

Doyle, R.G. 2008. Identification of Lithic Artifacts from Central Maine Coastal Archaeological Sites: A Case Study in Regional Lithic Acquisition Strategies. Flying Passage Press. Gardiner, Maine.

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