Internship Report Nate Stanley Center for Archaeological Studies

Transcription

1 Internship Report Nate Stanley Center for Archaeological Studies Introduction: Beginning in May of 2010, the center of Archaeological Studies (CAS) at Texas State University San Marcos conducted a cultural resource assessment for the Spring Lake Section 206 Aquatic Ecosystem Restoration Project (SLAERP). In June 2009, a Memorandum of Agreement (MOA) between the U.S. Army Corps of Engineers (USACE), Texas State University San Marcos (TxState), and the Texas Historical Commission (THC) regarding the Spring Lake Aquatic Restoration Project, San Marcos, Texas was signed and enacted (Ch. 1 SLAERP Draft Report, pg 1). The purpose of the SLAERP is to restore the natural habitats of Spring Lake and riparian (river bank) corridor/grassland adjacent to the lake. Procedures for this project are conducted under section 206 of the Water Recourses Development Act of 1966, which provides authority for the USACE to restore aquatic ecosystems (Ch. 1 SLAERP Draft Report, pg 1). The project will include the removal of all foreign plant species in the area as well as the removal of various structures, both terrestrial and aquatic, that used to serve the area when it was a theme park. In order to mitigate the potential impacts of the SLAERP will have on the cultural resources within the area of potential effect (APE), CAS performed both terrestrial and underwater cultural resource assessments. The results of CAS s assessments will inform the Historic Properties Treatment Plan, which will present recommendations for mitigating documented resources that will be affected by the SLAERP. A report that will present a summary of both a terrestrial and underwater cultural resource assessments of the APE is currently being written by Carole Leezer, the Principal Investigator of the cultural resource assessment and Associate Director of CAS. The present paper describes the project are in terms of environmental setting and cultural history. It then provides an explanation of the methods used in the field and in the CAS laboratory, and presents the results of this work. Project Area Setting: The San Marcos Springs, Sink Creek area in San Marcos, Texas is rich archaeological history. In 2001, Texas State took on a CRM survey directed under the supervision of Dr. Britt Bousman. This survey was done to examine the areas of Spring Lake and Sink Creek before removal of various structures along the Spring Lake peninsula, and the restoration of the Aquarena Springs Inn. The result of these surveys, spanning 1.7 m of an 8-9 meter thick intact alluvial terrace in the floodplain adjacent to the San Marcos Springs (Nickels, Bousman, 2010, 2), which actually provided evidence of human occupation dating from Paleoindian to Late Prehistoric (Nickels, Bousman, 2010, 2), was the most extensive report of the geomorphology for this area of Central Texas. There have been six prehistoric sites, dated to Paleoindian to Historic periods, done in the Sink Creek vicinity, although, none of these sites have gone below 2-3 meters (Nickels, Bousman, 2010, 47). Of the two studies focusing in geoarchaeology at Spring Lake-Sink Creek in 1999, neither offered any datable or

2 time-diagnostic materials, however, both offered radiocarbon dates. In the site done by Arnn and Kibler, backhoe trenches uncovered buried features along the valley escarpment. These finds indicated the presence of at least 2 m of Late Holocene colluvium, which is loose dirt found at the base of a hill (Nickels, Bousman, 2010, 47). In the second study, the earth coring technique was used where excavators too core samples from the immediate environ of the springs in Spring Lake. This test recovered two large humate radiocarbon ages, the oldest being Clovis at 11,470 ±100 B.P. at the base of the alluvial valley fill at a depth of 8.6 m (Nickels, Bousman, 2010, 47). A younger humate date of 3660±50 B.P. came from 2.4 m. It is true that these dates are mere estimates, but these estimates exhibit great importance of Sink Creek valley as an enduring prehistoric reserve in the history of central Texas archaeology. The Area of Potential Effect (APE), which is the area proposed to be disturbed, includes two archaeological test sites, 41HY160 (41=state number, HY=county: Hays, 160=site number) and 41HY165, as well as four other sites adjacent to it, 41HY37, 41HY147, 41HY161, and 41HY306. CAS conducted 196 shovel test units, three test units, and four backhoe trenches in three sections of the APE. This is not the first time for these sites to have archeological tests done in their vicinity. The dates of previous excavations and surveys run as far back as 1978 at site 41HY161 and 41HY147 by Joel Shiner. Both were underwater survey sites that produced profuse evidence of Archaic and Paleoindian Clovis occupation, although the artifacts were not found in stratigraphic areas that could be used to accurately reconstruct the lifestyle of the occupants at that time (Nickels, Bousman, 2010, 26). Methods of Excavation and Artifact Processing Shovel Testing CAS archaeologists conducted196 shovel test units in three sections of the APE. The first section is 75 ft wide and includes the area of the River Systems Institute Building to the Salt Grass parking lot on the northwest side of Spring Lake. The second section is ft wide and includes both sides of Sink Creek, extending through the Texas State Golf Course to Bert Brown Street. Section 3 includes the entire Aquarena Center. Section I includes part of the Aquarena Springs Amusement Park. 31 shovel test units were carried out in this area, all spaced about 15 meters apart because of the dense vegetation and need for a consistent scientific approach to the testing procedure. On average, the depth of these units was 40 cmbs (bs=below surface), which is where the excavators typically encountered bedrock. A total of 410 artifacts were recovered from Section I and include such things as bone, building materials, carbonized plant remains, ceramics, glass, lithics, metal, organics, personal item, and shell categories, as well as a biface hand axe (CAS, Interim Fieldwork Summary Report, pg 6). The outcome of the excavations at Section 1 led CAS to determine that the demolition continue in this area, since the prehistoric artifacts were found in an area that lies outside the area of impact. Section II is a grassy area around the bank of Sink Creek where the majority lies within the Texas State Golf Course and a small part inside the East Athletic

3 Fields. CAS archaeologists conducted 119 shovel test units, yielding 1123 artifacts, in Section II at average depths of 50 cmbs and set approximately 15 meters apart. At 50 cmbs, excavators experienced dense clays, which disallowed further depth. Artifacts such as bone, shell, glass bottles, metal, and building materials were found in this section. This was on of the areas where previous excavations had taken place in 2000 and 2001, termed the Front Door Project (CAS, Interim Fieldwork Summary Report, pg 7). The lithic deposits were found in dense areas on the surface next to the Number Eight green and between the Athletic Field and Sink Creek (CAS, Interim Fieldwork Summary Report, pg 9). Section III included 54 shovel test units at average depths of 60 cmbs spaced approx 15 meters apart. More dense clay was run into at 60 cmbs, so that is where excavation typically stopped. 400 artifacts were recovered from this section which included fragments of brick and tile, C14 (charcoal), bone, glass both window and vessel, metal, shell, wood, and seed fragments, as well as 160 lithic fragments. Artifacts such as the glass, marbles, and metal were evidence of the area having been used as a theme park. The classification of lithics included biface fragments (n=4), cores (n=2), debitage (n=79), fire-cracked rock (n=69), and projectile points (n=2) (CAS, Interim Fieldwork Summary Report, pg 10). There were sections of prehistoric lithic deposits around Aquarena Springs parking lot, which were further tested with backhoe trenches and 1 x 1 meter test units. The results of the shovel tests were four Archaeologically Sensitive Areas (ASA) that included intact cultural deposits within sites 41HY160 and 41HY165. These areas are considered archaeologically sensitive because the proposed construction may well disturb the intact cultural deposits (CAS, Interim Fieldwork Summary Report, pg 23). Test Units There were also three test unit excavations done (XU01, XU02, XU03) to further examine the areas that held heavy prehistoric lithic deposits. Further test units could not be carried out because of time restraints. XU01 and XU02 were done within the boundaries of Section III and were 1 x 1 meter test units. Although these test units together yielded a total of approx 261 artifacts, and that CAS determined these findings to be indicative of a prehistoric presence of the area (CAS, Interim Fieldwork Summary Report, pg 12), both of these test units were terminated and declared to be disturbed because of pipelines that were uncovered at about 67 cmbs. XU03, which was also excavated by an archaeological field school in 1996 and 1998, was within the boundaries of 41HY165 within Section II and went to a depth of 150 cmbs. This unit yielded a burned rock midden, two projectile points at 70 cmbs and 70.5 cmbs, a large bison bone which was submitted for radiometric dating, and other materials such as bone, carbon, prehistoric ceramics, glass, lithics, metal, and burned clay (CAS, Interim Fieldwork Summary Report, pg 13). Any further depth would have resulted in unsafe work environment since depth below 150 cmbs could cave in on the archaeologist inside the test unit. One 5-gallon bucket of soil from each level of all three test units was gathered. Then, soil samples of 4-liter bags from each bucket were placed into

4 separate 5-gallon buckets, filled with water, and stirred to loosen any floatable material in preparation for water screening. The buckets are also tagged, or labeled, to note exactly what unit, lot number, and level in cm the samples came from. My primary job at the beginning of my work here at CAS was to water screen these soil samples in ¼ and 1/8 screens. The purpose of water screening is to gather organic matrix info that can tell a lot about the environment at that time in history. I also floated the soil samples, although it was purely for experience in XU01 and XU02 since those two units were disturbed. After the buckets had been filled with water and left to sit for approx minutes, mesh-like cloth called cheesecloth was used to skim the floating organic material at the top of the water. Floatation is a crucial process in the methodology of artifact processing because it yields microscopic data that can be used to date the site area and understand more about the natural environment at that time. Backhoe Trenches There were also four backhoe trench excavations done in the Spring Lake vicinity in order to examine depositional history/environment and the potential for intact archaeological deposits within the APE (CAS, Interim Fieldwork Summary Report, pg 16). Two backhoe trenches were dug in the potential direction (deemed potential since disturbance in stream flow may have occurred as a result of damming or flooding) of the stream flow, and two were dug perpendicular to the stream flow. Backhoe trenches are ways of looking at the stratigraphic sequence of the soil. It is like looking back in time at how the soil had changed, either by man or as a result of nature itself, as well as to optimize the recovery of artifacts. A single vertical section was chosen for each backhoe trench for examination. Although, when variance occurred in the sections, adjacent walls were inspected for additional evidence (CAS, Interim Fieldwork Summary Report, pg 18). Each stratigraphic level is considered a zone. Zones are differentiated by color, texture, structure, and whatever materials other than the soils are included within them. BHT 1 (backhoe trench one) contained low amounts of flakes uncovered at 25 cmbs. No other artifacts were located in situ within BHT 1. BHT 2, on the northern wall, yielded fire-cracked rock at approximately 35 and 110 cmbs, as well as a distinct cluster of burned clay at cmbs in the same wall. Unidentifiable faunal remains (bone) as well as lithic debitage were uncovered, but no diagnostic artifacts were found in situ--therefore making it impossible to estimate cultural periods associated with those [these] artifacts (CAS, Interim Fieldwork Summary Report, pg 22). BHT 3 was similar to BHT 2, with large collections of in situ fire-cracked rock at around cmbs, which was the maximum depth, and lithic debitage at around 65 cmbs. The majority of the artifacts, including two projectile points which are not yet identified, were in horizontal regions with light scattering of other artifacts between them. CAS concluded that none of the recovered artifacts link with a certain cultural period (CAS, Interim Fieldwork Summary Report, pg 22). BHT 4, which was south of the field school 41HY160, did yield in situ artifacts such as fire-cracked rock and lithic debitage. The lowest point of this trench was at 135 cmbs, where the majority of the fire-cracked rock, lithic debitage,

5 and unidentifiable faunal remains were found. Although BHT 4 findings correlate consistently with the 41HY160 field school s findings, no diagnostic artifacts were found to help date the time period of the site. There were two main objectives to the backhoe trenching method: 1. To better understand how sediments were deposited in the area of potential effect to see where artifacts may be at this time, and 2. To record any archaeological deposits not previously recorded (CAS, Interim Fieldwork Summary Report, pg 23). CAS determined that the majority of the soil deposits are alluvial (water carried) in nature and that the position of the found artifacts were a result of periods of flooding in the area, but some in situ weathering of organic material was also present (CAS, Interim Fieldwork Summary Report, pg 23). The cultural deposits were mapped and the cultural materials observed in BHT 2, 3, and 4 were documented and preserved for future processing. Sorting Some of the most crucial information comes from sorting, although it is the most tedious part of archaeological lab work. This process is what has been taking up the majority of my time in the lab. After materials are screened or floated, they are put onto newspaper, which are laid on screens and set on a rack in the lab to dry. One of the most important things in this process is not to mix the ¼, 1/8, and floated materials. Should this happen, the materials are deemed disturbed and useless as context artifacts. The materials are also labeled by which unit, lot number, and level in cm they came from. The materials are left to dry on the racks for 1-2 days. After they have dried, lab workers look through the material using tweezers. All like material are placed together in separate piles to be bagged, labeled, and stored in the lab or sent to other labs to be dated. THC had given us a lab manual by which to follow when labeling these artifacts. CAS has a lab manual as well, and both were used as reference in labeling all sorted material. Categories of sorted materials included organic, lithic, metal, glass, and other (being a material that was unidentifiable). Organics were broken down to faunal remains, plant, wood, rootlets (individual root strands, yes we had to pull out every single one), nutshell, snail shell, insect exoskeleton, and C14 (charcoal). These categories were also broken down into more specific types, for example: sticks and bark were two different categories of wood; vertebra and bone fragments were different categories of faunal remains. Lithics were organized into categories such as lithic debitage, meaning tiny flakes of chert (the main mineral used to make stone tools), burned clay, which was red in color as well as had a distinct bumpy exterior, FCR (fire-cracked rock) which included a lot of limestone, petrified wood, and the sorted material which was mainly composed of soils not broken down in the floating and water screening processes. Veronica, one of CAS s previous interns and now lab technician and excavator, found a small projectile point smaller than a pinky fingernail. This gave immense cultural context to the unit and layer it was found in and was hailed as an intrinsic find. There was one artifact from XU03 that was particularly beautiful. It was a perfectly shaped projectile point, about the size of an adult thumb, made of petrified wood. You can see the wood grain lines running throughout the entire artifact, a truly outstanding combination of natural

6 phenomena and human technology. I had also found three small, white, spongy materials in XU03 at level 12, which was one of the deepest levels. After consulting with Carole Leezer, Associate Director at CAS and head of the SLAERP excavation, the material was wrapped in foil, marked is as other, and labeled as a possible fungus. Wrapping foil around some materials is a good way to keep them from fragmenting, especially when you have a very small amount. C14 is the main artifact we wrap with foil because even a small amount can be used to date the site from which it came from. Although, larger samples are preferred because small samples, the size of a pencil led tip, can cost up to $600. Metal artifacts were organized into categories such as nails, buttons, washers, tin, and other being metal that were not readily recognizable. Each bag of artifacts contained a small, rectangular paper containing the provenience information, which was the site name (SLAERP) unit number (XU01, 02, 03) level (1, 2, 3, ect) which also included depth in cm, the type of artifact (lithic, organic, metal, glass, other), description of the artifact (any further categorizations of the type as well as defining features), number of artifacts included in the bag (for this section, when the number clearly exceeded 200 it was not required to count the artifacts unless otherwise directed), weight of the entire sample in grams, date the sample was sorted, and the initials of the lab worker who sorted the material. Labeling Another tedious and steady handed job CAS lab attendants are rein was the labeling process of the lithic and ceramic artifacts. Each artifact had to be labeled with the site name (SLAERP) and lot number. A mixture of acetone and plastic in the shape of small spheres was made to create a sticky plastic that was lightly spread on a small, non-diagnostic portion of the artifacts. The mixture made a clear, plastic coating on the artifact where the provenience information was written. Black calligraphy pens were used on light colored artifacts and white or silver gel pens were used on darker colored artifacts. As a rule of thumb, labs are generally not required to label anything smaller than a quarter. But THC s lab manual said nothing about the quarter technique, so it was up to us to decide whether something was entirely too small for the label to actually be legible. Only the bags containing certain important artifacts, such was ceramic fragments, projectile points, other large to medium sized chert flakes, glass, brick, and FCR, were required to have labels. Results: CAS concluded that, with the Archaeologically Sensitive Areas containing cultural deposits, the presence of the Spanish Mission, and abundance of late prehistoric occupation (CAS, Interim Fieldwork Summary Report, pg 30), the APE may well contain shallow human burials. Because the ASA is within or right next to the APE, they are associated with a recorded State Archaeological Landmark (CAS, Interim Fieldwork Summary Report, pg 30). Because the extent of the information of the ASAs is hard to determine at this point, CAS has offered preliminary cautions and recommendations to aid in protecting any artifacts that may turn up in the process of the demolition/construction projects.

7 CAS recommends rerouting the paths of the heavy machinery that will be used in removing the buildings to areas that do not go directly though the APE as not to disturb any burials. Also that test units of 1 x 1 meter to a depth of 70 cmbgs (below ground surface) be excavated, the number of which would be determined between 10% and 1% of the APE that will be affected by the demolition (CAS, Interim Fieldwork Summary Report, pg 31). As agreed upon in the memorandum, the demolition of these structures should be monitored at all times by a professional archaeologist(s) (CAS, Interim Fieldwork Summary Report, pg 31). Of course, temporary delay of the project will ensue should any archaeological artifacts be unearthed. Although only 6 inches of soil are said to be disturbed in every ASA, CAS concludes that the machinery needed to take out the vegetation will corrupt potential artifacts. Precautions regarding the removal of exotic vegetation are also recommended by CAS such that, unless the vegetation removal is done by hand, limited data recovery be conducted in the areas where the removal of non-local vegetation will occur (CAS, Interim Fieldwork Summary Report, pg 31). A professional archaeologist is also required to monitor all vegetation removal, and, should any archaeological artifacts be unearthed, temporary halting of the demolition ensue until the artifacts are removed and preserved.