Herbert Haas

Dating of Holocene Stratigraphy With Soluble and Insoluble Organic Fractions at the Lubbock Lake Archaeological Site, Texas: An Ideal Case Study

The Lubbock Lake site, on the Southern High Plains of Texas, contains one of the most complete and best-dated late Quaternary records in North America. A total of 117 14C dates are available from the site, determined by the Smithsonian and SMU Laboratories. Of these dates, 84 have been derived from residues (humin) and humates (humic acids) of organic-rich marsh sediments and A horizons of buried soils. Most of the ages are consistent with dates determined on charcoal and wood, and with the archaeologic and stratigraphic record. The dates on the marsh sediments are approximate points in time. Dates from the top of buried A-horizons are a maximum for burial and in many cases are close to the actual age of burial. Dates from the base of the A-horizons are a minimum for the beginning of soil formation, in some cases as much as several thousand years younger than the initiation of pedogenesis. A few pairs of dates were obtained from hurnin and humic acid derived from split samples; there are no consistencies in similarities or differences in these age pairs. It also became apparent that dates determined on samples from scraped trench walls or excavations that were left open for several years are younger than dates from samples taken from exactly the same locations when the sampling surfaces were freshly excavated.

Radiocarbon Ages From The Lubbock Lake Site, 1950-1980: Framework For Gul Tural And Ecological Change On The Southern High Plains

The Lubbock Lake site is a well-stratified ar chaeological locality on the Southern High Plains of Texas. It contains a thick sequence of late Quaternary deposits with associated soils and cultural, faunal, and floral remains. Sixty-seven radiocarbon ages thus far are available from the site, providing a well-dated chronology spanning the past 11,000 years. Radiocarbon ages were determined on a variety of materials including wood, charcoal, shell, bone, organic sediments, and A horizons. Some of these materials pose certain problems of inter pretation but with proper caution and evaluation provide useful ages.

Radiocarbon Dating of Boise Apatite Using Thermal Release of CO2

Extraction of carbon from bone hydroxy apatite as CO2 by heating in an oxygen atmosphere is an alternative method to hydrolysis of the bone. Heating in specific steps allows separation of CO2 fractions from different sources, including weakened or sound bone material and secondary deposits. Pretreatments to remove most secondary carbonate and much of the collagen are necessary. Thermogravimetric (weight loss) curves and CO2 release patterns during heating show that the temperature interval for collection of the most reliable CO2 sample for dating purposes lies between 800 and 950°C. Age dates run on such samples support this conclusion.

Southern Methodist University radiocarbon date list II.

The SMU Radiocarbon Laboratory is operated by the Department of Geological Sciences within the Institute for the Study of Earth and Man. One laboratory room contains the benzene synthesis system where samples are pretreated and converted to CO 2 in a standard way and gas is purified after the procedures of Broecker (1957) by passage through hot CuO, 10% AgNO 3 solution, chromic acid, hot copper, and P 2 O 5 via cryogenic pumping with liquid nitrogen. Purified CO 2 is then converted to Li 2 C 2 which is hydrolized to C 2 H 2 and converted to C 6 H 6 catalytically following the procedures of Noakes et al (1966). Carbon dioxide and benzene yields are routinely in excess of 90% in both cases.

Radiocarbon Ages Form the Lubbock Lake Site: 1981-1984

Forty-eight additional radiocarbon ages became available for Lubbock Lake (Southern High Plains of Texas) during the period 1981-1984. A new but un reliable radiocarbon age is available from Stratum 1 (deposition ending about 11,000 years B.P.; Clovis age occupation). Thirty-three new radiocarbon ages are available from Stratum 2 and suggest the follow ing refinements to the previously established radio carbon chronology for the deposit: (1) the initial phase of lacustrine (diatomite) deposition lasted from 11,000 to about 10,500 years B.P. (early Folsom occupation); (2) the first cycle of marsh (organic-rich clay) sedimentation occurred between about 10,500 and 10,200 years B.P. (late Folsom occupation); (3) the substrata 2A-2B contact is not time-transgressive and dates to 10,000 years B.P. or a little less (Plain view occupation); (4) near-shore deposits (substratum 2s) are facies of all or portions of substrata 2A and 2B; (5) eolian sediments (substratum 2e) began to accu mulate by 9000 years B.P. (early Firstview occupa tion); and (6) the Firstview Soil developed in upper substratum 2B beginning about 8500 years B.P. (First view occupation) and ended as late as 6300 to 6200 years B.P. (early Archaic occupation), which also would be the age for the beginning of Stratum 3 deposition. Both new and previously reported radio carbon ages from upper Stratum 3 and lower Stra turn 4 suggest that the Yellowhouse Soil formed in Stratum 3 along the valley margins during the period 5500-5000 years B.P. (middle Archaic occupation). At this time along the valley axis, Stratum 3 was eroded and then substratum 4A was deposited as a result of increased spring activity. New radiocarbon ages from charcoal further document human activity at Lubbock Lake during the Protohistoric (Garza) period. The ad ditional radiocarbon ages from Lubbock Lake strength en the position of the site as one of the best-dated sites in North America.

Radiocarbon Dates Of Old And Middle Kingdom Monuments In Egypt

Between 1984 and 1995 over 450 organic samples were collected from monuments built during the Old and Middle Kingdoms. The most suitable samples were selected for dating. The purpose was to establish a radiocarbon chronology with samples from secure context and collected with the careful techniques required for 14 C samples. This chronology is compared to the historical chronology established by reconstructing written documentation.

Radiocarbon evidence for Holocene recharge of ground water, Western Desert, Egypt.

During Pleistocene pluvial precipitation was sufficient for the maintenance of groundwater supported lakes and for the accumulation of playa lakes in wind-scoured depressions during the early Holocene pluvial. At places where ground water reaches near to the surface, wells (birs) have been dug and maintained in historic times. These birs have been used as sampling sites for water analyses, including carbon-14 levels, carbon and oxygen stable isotope ratios, tritium concentrations, and chemical data. All the waters from birs analyzed to date produced apparent radiocarbon ages ranging from late historic to early Holocene, and tritium analyses on some of these indicate no recharge during the Atomic age. Sources of error for the radiocarbon analyses, including exchange with atmospheric CO2, respiration by plant roots, and contact with carbonates of considerably older age, were evaluated. None of these factors have such an extreme impact on the measurements as to render the result invalid. Two trends revealed by these data are an increase in apparent age from northwest to southwest and with subsequent extractions at the same site where the hand-dug well was bailed out and sampled four times within two days. We conclude that recharge of shallow ground water occurred in early Holocene time, and some recharge of deeper aquifers may have occurred where infiltration paths permitted. Some recharge occurred in late Holocene (post pluvial) time, but the net trend has been toward hyper-aridity that characterizes the area today.

Comparison of vanadium oxide catalysts for synthesis of benzene; benzene purity, yields and reconditioning methods.

This study compares vanadium oxide catalysts from three different sources: Noakes (N), Harshaw Chemical (H) and Kh. Arslanov at the St. Petersburg State University, Russia (R). The catalysts are used to convert acetylene to benzene in the last step of benzene synthesis. The organic purity of benzene in all three catalysts is high; 99.91-99.93% for (N) and (H) and 99.87% for (R). The benzene yields range from 90.0 to 94.3%. (N) averaged 92.6%, (H) averaged 91.1% and (R) averaged 92.0%. A conversion residue in the catalysts was analyzed for delta (super 13) C and found to be isotopically lighter relative to acetylene by -2.2 per mil for (N) and (H) and -3.9 per mil for (R). Benzene yields were studied on different reconditioning methods applied to all catalysts: heating to 400 degrees C in air averaged 92.3%; the same temperature with a half and half mixture of O (sub 2) and Ar averaged 91.9%, adding a half and half mixture of H (sub 2) and Ar at 200 degrees C to the end of this treatment averaged 91.8%. Based on this research, the obvious difference seen between the catalysts is in their trace by-products.

Change of calibration parameters in frequently used vials in benzene scintillation counting

Scintillation counting vials used for counting synthesized benzene accumulate an inside coating which uble in benzene. This coating reduces the photon transfer from the vial and lowers its observed background. Agweh ciaclhc uisla itnisoonlsthat include calibration data collected with other vials may be inaccurate if this effect is not considered. Frequent cleaning of the counting vials with strong acid solutions keeps the coating from accumulating.

Mid-Wisconsinan radiocarbon dates from mastodon- and mammoth-bearing springs, Ozark Highland, Missouri.

From 1966 to 1979, the University of Missouri, the University of Arizona, and the Illinois State Museum conducted extensive interdisciplinary investigations of Late Pleistocene peat deposits associated with springs, some extinct, in the Pomme de Terre River Valley of the Ozark Highland, Missouri (fig 1). Most of the sites are now beneath the waters of the Harry S Truman reservoir. Archaeologic investigations in the area produced a remarkably long sequence of cultural change and development during the Holocene but produced no evidence of human presence in the area prior to 11,000 years ago despite diligent excavation of favorable bone-bearing deposits.