The effects of burrowing activity on archaeological sites: Ndondondwane,South Africa

Burrowing activity is a widely recognized source of site modification. Most taphonomic studies of burrowers emphasize their destructive aspects on the archaeological record. Excavations at Ndondondwane, South Africa, suggest burrowing activity is destructive in some ways, but may also preserve cultural behavior. Drawing on both direct and indirect sources of evidence, we discuss how burrowing activity by rodents, earthworms, and termites can inform about pedogenic and depositional processes at archaeological sites and both preserve and destroy evidence of intra‐settlement patterns and early African cultigens. Specifically, we demonstrate the limited effect of earthworms on site stratigraphy, how the localized activity of termites have preserved casts of early African cultigens, and how the ability of archaeologists to distinguish the devastating effects of rodent burrowing from remains of architectural features have permitted important inferences about social and ritual life in early African farming communities. © 2004 Wiley Periodicals, Inc.     

Radar measurement of small-scale surface texture: Syrtis major

Recent radar observations of Syrtis Major have shown it to be smooth and relatively homogeneous when sensed at centimeter wavelengths λ. There is a gradual decrease in surface roughness east to west across the basin, which correlates with an apparent decrease in small (< 1 km diameter) crater density. Root mean square surface slopes σ range from more than 1.5–2.0° in the east to less than 0.5° along the western margin at λ = 12.6 cm. The surface appears somewhat rougher at λ = 3.6 cm; a σ ∝ λ^?0.3 dependence is inferred. Radar reflectivity increases from about 5% to about 12% across Syrtis Major, being greatest near the western margin. High-resolution (8 to 20 m/pixel) Viking images suggest that an increasing amount of resurfacing has occurred in western Syrtis Major compared with the eastern parts. The radar, infrared, and optical imaing evidence are consistent with resurfacing by geologically recent, low-viscosity lavas which were subsequently mantled by thin layers of aeolian material. Each data set may be taken as a unique source of scale-dependent information on surface materials and properties. From comparison of radar-derived surface roughness with image-derived crater density curves we conclude that processes other than cratering control the surface texture on 0.03- to 100-m surface scales.     

1973 dust storm on Mars: Maps from hourly photographs

The hourly progress of the 1973 major Martian storm has been mapped using photographic images from the International Planetary Patrol. The outlines of brightened areas were definable for about 3 weeks, which is about the same amount of time that could be mapped in this manner during the 1971 major storm. Two series of 20 daily maps show the semihourly positions of the storm brightenings in red light and blue light. The maps indicate that the 1973 storm had many similarities to the 1971 storm, as well as a number of significant characteristics of its own. The differences in color and location of several initial clouds that developed during the 1973 storm are compared using Patrol photographs taken through red, green, blue, and ultraviolet filters. The positions of the 1973 initial clouds are shown on a map together with the initial clouds that developed into the well-known storms of 1956 and 1971. The 1973 storm developed more of the characteristics of the 1971 storm after 8 to 10 days. Separate maps of every 2 hours showing the progression of the storms on their 11th days portray the extent of the similarities. The 1973 storm was mapped through its 22nd day (November 3), by which time it had begun to decay: the brightened areas had diminished in size and contrast. A summary map shows which areas on Mars were most affected by the brightenings seen during this storm. The map is more comprehensive than could be produced from the 1956 and 1971 photographs, although the areas which were active throughout these three major storms were very similar. Not only was the general latitudinal belt the same, but also the irregularities or indentations in the belt occured at nearly the same places.     

A 30 million year cycle in Arctic volcanism?

Arctic perimeters volcanism has pulsed to a maximum approximately every 30 million years. This periodicity is similar to that observed on a global scale.     

Solid solution — aqueous solution equilibria as a function of pH

The equations relating element distribution and pH are derived for systems containing an ideal solid solution in equilibrium with an ideal aqueous solution, assuming no polymeric complexes form in the aqueous solution and the solid solution does not contain molecular units with multiple atoms of the substituting elements. These expressions demonstrate that the ratio of the partition coefficients describing element distribution for a system containing a multi-component solid solution is inversely proportional to the solubilities of the end member components at any given pH raised to the power equal to the ratio of the sum of the stoichiometric coefficients of the end-member salt to the stoichiometric coefficient of the substituting radical. The coefficient describing distribution between the aqueous phase and a two-component solid solution is equal to the inverse of the ratio of the end member solubilities raised to the above power. Element distribution between the two phases will be homogenous at any pH resulting in identical solubilities for the two end-member components, and a reversal in relative solubilities will result in a corresponding reversal in the element preferentially incorporated into the solid solution. Because of the dependence of element distribution on pH, a crystal could develop both zoning and reverse zoning as a result of changes in pH. The distribution coefficient could provide information regarding the pH of the aqueous solution at the time of mineral formation if independent evidence establishes the ratio of end-member components in the aqueous phase. The equations describing element distribution may be expressed in terms of the solubility products of the end-member components and the ionization constants of the substituting radicals. Based on the relative values of the ionization constants, pH intervals can be established in which only the concentration of a single complex for each substituting radical need be considered. Within such an interval, the curve of the log of the distribution coefficient vs. pH is linear with a slope equal to the difference in the charges of the two complexes. This approach to the examination of element distribution is developed in some detail for the geologically important case of a two component solid solution having composition (A²⁺, B²⁺) X^2?.     

Evaluation of magnitudes using USSR and US (NOS) techniques

Summary WWSSN seismograms for the Caucasus earthquake of May 14, 1970, and the Alma-Ata earthquake of June 5, 1970, were scaled form _b using techniques employed by USSR (P amplitude during first 20 seconds) and USA (P amplitude during first few cycles). USSR seismograms will be used in a second phase of this study. Using both techniques, the scatter at each station form _b (SPZ) was 0.0–0.3 with half of the stations having no scatter. The scatter among all of the stations was over 1 unit. Using both techniques, the scatter at each station form _b (LPZ) was zero except for NUR on May 14. The scatter among all of the stations was 1 unit on May 14 and 0.4 on June 5. This preliminary study indicates the scaling techniques have no effect in computingm _b (SPZ) andm _b (LPZ) but the differences are more likely related to source functions, crust and upper mantle response functions, and instrumental band pass.NOS Seismology personnel were transferred to NOAA-ESL in 1971.     

Simulation des Nitratabbaus im Grundwasser

Ten reaction vessels containing 1 m³ were used as the experimental arrangement. They were filled with coarse sand or fine gravel and installed 60 cm below the floor. The pore volume (water saturation) was 227… 260 l. Anaerobic conditions were established by the addition of 6 g glucose at storage. The reactors were given tap water with 50 and 200 mg/l NO from KNO₃ in such a way that a volumetric rate of flow of 0.2, 0.4 and 0.8 l/d was created. The volumetric rates of flow corresponded to the natural recharge of groundwater, the recharge of groundwater under the conditions of irrigation and the conditions of an intensive wastewater ground treatment. In the effluent from the reaction vessels the nitrate concentration was determined every month. It was stationary from the 7th to the 55th month after the beginning of the experiment. The experiments are evaluated by means of a model which takes into account the diffusion, convection and kinetics of the nitrate degradation according to Michaelis-Menten. A simple method for solving homogeneous non-linear differential equations of the second order is proposed. The experimental and model results show a good agreement and prove the very slow nitrate degradation in the groundwater with k_M = 210 mg/l, v_max = 1.5 mg/l · d or k₁ = 0.005 d^?1.     

The effects of alongshore variation in bottom topography on a boundary current—(topographically induced upwelling)

A theory which describes the constant f-plane flow of a steady inviscid baroclinic boundary current over a continental margin with a bathymetry that varies slowly in the alongshore but rapidly in the offshore directions is developed in the parameter regime (L_D/L)² ≤ Ro 1, where L_D is the internal deformation radius, L the horizontal length scale, and Ro the Rossby number. To lowest order in the Rossby number the flow is along isobaths with speed q_o = V_u(h,z)|Vh|/α, where V_u(h,z) is the upstream speed, α the upstream bottom slope at depth h, and Vh the bottom slope downstream at depth h. The lowest order flow produces a variation in the vertical component of relative vorticity along the isobath as the magnitude and direction of Vh vary in the downstream direction. The variation of vorticity requires a vertical as well as a cross-isobath flow at first order in the Rossby number. The first order vertical velocity is computed from the vorticity equation in terms of upstream conditions and downstream variations of the bathymetry. The density, pressure, and cross-isobath flow at first order in the Rossby number are then calculated. It is shown that in the cyclonic region of current (d/dh(V_u/α) > 0), if the isobaths diverge in the downstream direction ((∂/∂s)|Vh| < 0), then upwelling and onshore flow occur. The theory is applied to the northeastern Florida shelf to explain bottom temperature observations.