Meadowcroft PA

Introduction
The Meadowcroft Rockshelter was first excavated between 1973-1977. It is the site of the oldest well-dated evidences of man in the Americas, in addition to being the longest occupational sequence in the Western Hemisphere (Adivasio, 1977). This outcropping of sandstone has been a point of human occupancy for well over 12,000 years. While controversial, Meadowcroft has changed perceptions of early human migration patterns, in addition to providing evidence that humans were populating much of the Americas even before Clovis Culture. This paper will describe the structure and geological significance of Meadowcroft, and then will provide an overview of the radiocarbon controversy. However, it will not focus on discrepancies in dating, but rather the peoples who used the shelter for many years. Dates shown are mostly agreed upon, and where there are discrepancies this paper will use those which J. M. Adivasio states in his research.

Site Description
Meadowcroft Rockshelter is a 62m overhang comprised of Morgantown-Connellsville sandstone located 48.27 km South-West of Pittsburgh, PA (Adivasio, 1977). It is located on the north bank of Cross Creek, a small tributary to the Ohio river which runs 12.16km to the east. (Adivasio, 1977) The shelter overhang is situated some 15m above the modern surface floor, orientated in a rough East-West direction. This is beneficial due to the prevailing winds in the same direction, which allows for good ventilation for fires and insects (Adivasio, 1977).

The region is a temperate forest, with hackberry bushes, broad-leaf trees, and a mix of conifers. There are several similar creeks in the area which have been utilized by humans, Harmon creek slightly north, Racoon creek to the north-east and Buffalo creek in the south. Meadowcroft is located roughly fifty miles south of the maximum glacial expansion seen during the last ice age (Irving, 1985). The site itself is comprised of eleven distinct stratum which have been identified I - XI. The lowest layer, I, has been dated to 28,760-19,430 BC. While there is no evidence of human activities at his lowest layer, the subsequent layers document human activity up through the year 1775 AD (Adivasio, 1977).

The sediment filling the site is comprised of sand and stone of varying sizes, and filling the site through a variety of means. Large boulders and stones came by way of rock falls, sometimes in large number. Smaller sand grains constantly erode from the ceiling and walls, providing a constant fill of minute particle. The final sediment we see is made of clay-sized pieces which filled in during heavy rains and washes. ( Adivasio, 1977). There is clear evidence of a slowly receding drip line off the cliff top. This allows us to eliminate the possibility of large flooding as a means of sediment collection, as the drip line would have been eliminated (Adivasio, 1977).

Contamination
Prior to the publication of the excavation of Meadowcroft in 1975, the general consensus within Archaeology was that humans arrived in the Americas in the range of 11,500 years ago. However, radiocarbon dating at Meadowcroft showed human occupation 14,255 years ago with an earliest possible occupation being 16,770 years ago (Adovasio, 1990). This went in direct opposition to a widely believed notion of Clovis Culture being the first group to widely populate the Americas. Critics complained of flaws in the dating, and as a result subsequent dating was done by several different laboratories. None of the dates earlier to 10,200 were of any controversy. Nor were the dates at the deepest level dating to 28,760. The area in question was that of the lower stratum II, referred to as IIa. Samples taken from this layer include a carbonized fragment of bark-like material, possibly the remains of a basket. This piece dates to 17,650 BC. However, there are several issues as to what this sample actually is comprised up. Rather than a piece of â??good charcoalâ?� which is described as â??integral fragments of wood pyrolized to elemental carbonâ?� (Haynes, 1980). Some scientists speculate this is not a piece of charcoal butt a hodgepodge of charcoal pieces intermixed with other organic particles (Haynes, 1980). This distinction, while small, makes a big difference in dating the material and the chemical washes which all samples undergo in laboratory dating. Skeptics point to a site named Tule Springs in which archaeologists mistakenly thought pieces a decayed wood were in fact burnt wood as evidence of misdating samples. Other possibilities for contamination include theories involving groundwater pushing older pieces of organic matter up through layers and depositing them. There is evidence that the water table has not risen significantly in the past, and that would put even the lowest levels of the shelter well above the waterline making this an unlikely possibility (Adivasio, 1977).
While skeptics are not satisfied, all of the artifacts found at Meadowcroft have been meticulously mapped, documented, tested and dated by several reputable laboratories. Recently several other sites have been discovered which also lead to human occupation prior to 11,500 years ago. One of the more notable is Monte Verde in southern Chile dating to 12,500 years ago.


Functions
The role of Meadowcroft is that of a hunting base camp, or food-processing area (Adivasio, 1977). It has been used intermittently well into the time of European contact. Artifacts found in the shelter can be grouped into seven categories: lithic, bone, wood, shell, basketry, cordage, and ceramics. The most common finds are fire pits and hearths, along with refuse and storage pits (Adivasio, 1977). Animal bones have been found, mostly being whitetail deer and elk, but also mollusks, birds, squirrels, and fish. The plant remains consist of both charred and uncharred hackberry seeds, along with walnuts and pollen grains. Both plant and animal remains have been found in all layers starting from IIa through XI (Adivasio, 1977). From the time of earliest occupation people are using the shelter for hunting and gathering activities. Other than limestone choppers, the tools are not being made at the site, rather they are being reworked. The tools are of high quality stone, not locally found. It is either traded for, or picked up as the people travel their seasonal migrations. Located in stratum IV are two artifacts of maize dating to 340 BC and 375 BC. Found in the same layer are pieces of squash dating to 870 BC and 865 BC. This is the earliest known occurrence of both domestic species in the upper Ohio valley. This brings the possibility that both plants were more widespreadly known that earlier thought (Adivasio, 1977). In the stratum younger than where these plants are found there is less evidence of gathered plant remains. While possibly due to sampling variations, it also points to the natural decline of gathered foods with the availability of cultivated foods.

These variations in food remains, can tell us quite a bit about the populations using the rockshelter. Scientifically we are able to analyze the remains and date them, catalog them and draw conclusions. Archaeology in this respect is like the other hard sciences, using empirical data to support our conclusions. However archeologists are both scientists and humanists (Irving, 1985). As Archaeologists, the goal is to find the Material Culture at a given site. As Anthropologists we look at that data and add the human touch to it. We can imagine and assume what it was like in the daily struggle for our earliest ancestors. The people using Meadowcroft were not living there year-round, nor was it occupied by any one group of people. Meadowcroft provides a continual link through stratigraphy from European contact back thousands of years. There are no fluted points at Meadowcroft like what we see with the Clovis Culture. But we find in stratum IIa, buried beneath a rock fall which happened in the year 10,000 BC is a bifacial lanceolate point which is morphologically similar to points found in Ft Rock Cave, OR, Bonfire Shelter, TX, and Ventana Cave, AZ. Similarities over such a widespread area does not mean that these people were in direct contact with each other but it hints at a larger, more complex picture of pre-Clovis people. Humans in the Western Hemisphere could quite possibly have spread faster that earlier thought, or arrived before the opening of the ice-free corridor.

Conclusions
The Meadowcroft Rockshelter is not the largest site in the Americas. Nor is it especially interesting as a rockshelter. What is important however, is the stratigraphy and radiocarbon dating. Meadowcroft is the oldest continually occupied site in the Western Hemisphere. If the radiocarbon dates are correct, which I believe them to be, Meadowcroft would also be one of the largest examples of pre-Clovis people in the Eastern Woodlands. There is speculation and controversy over contamination and radiocarbon dating, possible theories include groundwater swelling and contaminating the layers, coal and vitrine samples getting mixed in with samples, or misidentification of samples. However all the controversy has led to more refined techniques of dating and shown the importance of accurate field work. If people were habiting Meadowcroft 17,650 BC then this also means they are elsewhere in the region. Such possibilities raise new questions on how and when humans first came to the Americas. It challenges assumptions on how technologically advanced pre-Clovis lived and dispersed. Other sites have since been uncovered and researched which supports the possibility of human inhabitation prior to the ice free corridor around 11,500 BC.