Uwharries Lithics Dr. Randy Daniel

Thursday Morning
February 25, 1999
8:00 - 11:40
Field Trip to Morrow Mountain
with Dr. Randy Daniel

[Field Trip Scrapbook]

We're here at Morrow Mountain. I will make some comments on why the site is significant and then we're going to take a short walk down the side of the mountain to an erosional feature on the hillside. There you will see what I think exemplifies the density of material on the mountain, and get a feel for the amount of prehistoric quarrying that has taken place here.

We are located at the southern end of the chain of mountains called the Uwharries. The northern edge is in Asheboro where we were earlier this morning, about 46 kilometers away. The southern half of the Uwharrie Mountains is an area that was extensively quarried. It was in this area that Bob Butler and I began our research in 1990. We were interested in looking at the Uwharries as a quarry region. Of course, our work was not the first to identify quarries here. There had been a number of earlier archaeological studies in Morrow Mountain State Park, and in the Uwharrie National Forest across the Yadkin River. But what Bob and I wanted to do was systematically survey the area for quarries, sample them petrologically, and begin to trace the movements of the stone across the state. Archaeologists in North Carolina have known about the Uwharries for decades but they didn't really know the exact relationship of the Uwharrie lithic materials to the Hardaway Site (which we'll visit later today as part of the field trip).

The Uwharries are part of the Carolina Slate Belt. We're on the eastern edge of the Slate Belt, and as you probably know, the Slate Belt was formed hundreds of millions of years ago. The Uwharries were formed as a result of volcanic events that deposited massive amounts of lava and ash in the region. Although the Uwharries are called mountains, they're actually what geologists refer to as inselbergs. That is, they are essentially remnants of a massive erosional event that took place on an ancient and higher peneplain in the Miocene. So even though the deposits that we're standing on may be several hundred million years old, the erosional event that created the mountains is only a couple of tens of millions of years old.

There are three main geologic or lithologic units in the Uwharries. The bedrock in the region is argillite. In fact, argillite forms the bed of the Yadkin River. Argillite is a meta-sedimentary rock that exhibits a sheet-like bedding. It is relatively soft as compared to rhyolite. Although it can be knapped, it has a cleavage-like plane to it, which, as you know, inhibits a good conchoidal fracture.

Greenstone is the second lithologic unit and it sits on top of the argillite.. Rhyolite, in turn, lies above greenstone. The Hardaway site, by the way, is lithologically situated on greenstone rather than rhyolite. Rhyolite is what all these little chips are made of scattered on the ground. Rhyolite is a fine-grained metamorphic igneous rock-an extrusive volcanic flow. In fact, you get two kinds of extrusives: rhyolitic flows or lava which is what this is, and volcanic ash, which forms the rhyolitic tuffs more common in the northern portion of the Uwharrie Mountains. One of the characteristics of Morrow Mountain rhyolite, is flow banding. There's a hint of this flow banding in this unweathered specimen. You can see the flow lines across here but on the more weathered specimens it is more pronounced: you'll see a sort of zebra-like appearance, which is very distinctive. Rhyolite is made up primarily of quartz and feldspar with a high silica content which gives it a good conchoidal fracture.

There's a couple of other geological terms that are useful in describing rhyolite. One is the term aphanitic, which refers to its very fine-grained ground mass. Morrow Mountain rhyolite is so fine-grained that you can't see the mineral composition with your naked eye. Some rhyolite, however, has larger crystals in the ground mass that can be seen with the naked eye. It is called porphyritic, and the larger crystals are referred to as phenocrysts. I have some samples of that type that are from the park. Porphyritic rhyolite was also exploited prehistorically and we have identified several of these quarries in our survey. Morrow Mountain rhyolite, in contrast, is aphyric. That is, it lacks phenocrysts. And I think this difference is significant from a knapping perspective. Some of the flintknappers who have worked with this stuff tell me, that they'd rather work this aphyric rhyolite than the porphyritic rhyolite. My guess is that the presence of phenocrysts hamper the quality of the conchoidal fracture.

The other interesting thing that I found out in working with Bob [Butler] is that rhyolite is compositionally very similar to obsidian--the volcanic glass found mostly in the western United States. I like to think of rhyolite as the eastern equivalent of obsidian. And this is due to its good concoidial fracture. Rhyolite, to me, is THE "righteous" rock of North Carolina. It appears to be the dominant raw material type in the Piedmont. We lack cherts for the most part, although we know of one or two chert quarries in the region, but you only have to look at any collection to understand that metavolcanic stone is the stone of choice here in North Carolina. Cherts are very, very rare until you get to the mountains where you get the influx of the Ridge and Valley [Tennessee and western Virginia] cherts.

Finally, I'd like to say a word about the history of Morrow Mountain itself. When we began doing the research, I tried to identify when Morrow Mountain was first reported as an archaeological site. Of course, the site had been known for decades. It was first recorded in 1958 in the site files of University of North Carolina Chapel Hill by Stanley South. There's some irony here in that Stanley South, the southeast's most prominent historical archaeologist, reported the most significant prehistoric quarry in the state. But it's not until recently, working with Bob, that I began to realize the real significance of Morrow Mountain: it appears to be the primary stone source for the tool assemblage from the Hardaway Site. About 70 percent of the assemblage from the Early Archaic component-Dalton, Palmer, and Kirk complexes-apparently comes from an aphyric rhyolite that most likely has its origins here on Morrow Mountain. We're about four or five miles from Hardaway.

So, as I said, in 1990 and 1991, Bob and I set out with essentially one simple question, not that it had a simple answer. I wanted to know, what was the source or sources of the stone in the Hardaway assemblage? I looked to Bob Butler [late of the University of North Carolina] for answers, as he was a geologist who had some 30 years experience doing geology here in the Piedmont. Bob looked at the assemblage and then said, "Well, it's probably from the Uwharries. . .I'll bet it's right around in the vicinity of the Hardaway Site." And that led us to survey the the Uwharries where we recorded about 27 or so quarries. And that, in a nutshell, is the story of our research. So let's walk around. . .and you can enjoy the sights.


Presentation Lithic Debitage
Dr. Randy Daniel makes his presentation to the Conference atop Morrow Mountain Morrow Mountain is literally paved with debitage from quarrying activites at the site
Erosional gulley
Numerous erosional gulleys have exposed not only lithic outcrops but surprisingly thick deposits of lithic materials along their banks.