Royal Cemetery, PG779, excavated artifact, #U.11164, Standard of Ur, War Side, upper left: detail of 1st to 3rd registers: detail

Ur (deserted settlement), Iraq; shell, lapis lazuli, red limestone; set in bitumen

Royal Cemetery, PG779, excavated artifact, #U.11164, Standard of Ur, Peace Side

Ur (deserted settlement), Iraq; 8 35/64 in. x 1 ft. 7 27/32 in. x 4 9/16 in.; shell, lapis lazuli, red limestone; set in bitumen

Royal Cemetery, PG779, excavated artifact, #U.11164, Standard of Ur, left end

Ur (deserted settlement), Iraq; 8 35/64 in.x 4 9/16 in.; shell, lapis lazuli, red limestone; set in bitumen

Royal Cemetery, PG779, excavated artifact, #U.11164, Standard of Ur, right end

Ur (deserted settlement), Iraq; 8 35/64 in.x 4 9/16 in.; shell, lapis lazuli, red limestone; set in bitumen

Royal Cemetery, PG779, excavated artifact, #U.11164, Standard of Ur, War Side

Ur (deserted settlement), Iraq; 8 35/64 in.x 1 ft. 7 27/32 in.x 4 9/16 in.; shell, lapis lazuli, red limestone; set in bitumen

Former Ocoya Landfill Site : Livingston County, Illinois.

Illinois EPA's initial evaluation of this site revealed problems such as erosion, exposed waste, low areas at the surface that allowed water to pond, and leachate seeps water that becomes contaminated after contact with landfill waste).

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Rackham Blg. [Building] construction

View is toward west. Exterior limestone in progress. No. 14 of chronological series of construction photographs, numbered 1 to 32. Smith, Hinchman & Grylls, architects. W.B. Wood Co., construction

Rackham Blg. [Building] construction

View facing west. Limestone exterior in progress. No. 15 of chronological series of construction photographs, numbered 1 to 32. Smith, Hinchman & Grylls, architects. W.B. Wood Co., construction

Rackham Blg. [Building] construction

View toward north. Additional steel framework on upper floors. More exterior limestone on main floor. No. 17 of chronological series of construction photographs, numbered 1 to 32. Smith, Hinchman & Grylls, architects. W.B. Wood Co., construction

Rackham Blg. [Building] construction

View toward north. Steel framework for roof of building nearly complete. Exterior limestone on second floor. No. 18 of chronological series of construction photographs, numbered 1 to 32. Smith, Hinchman & Grylls, architects. W.B. Wood Co., construction

Rackham Blg. [Building] construction

View toward north including cityscape. Limestone in progress on second floor. Roof is being prepared for finish. Finishing stonework on first floor. Additional scaffolding from east tower to roof. No. 24 of chronological series of construction photographs, numbered 1 to 32. Smith, Hinchman & Grylls, architects. W.B. Wood Co., construction

Use of a probabilistic neural network to reduce costs of selecting construction rock

Rocks used as construction aggregate in temperate climates deteriorate to differing degrees because of repeated freezing and thawing. The magnitude of the deterioration depends on the rock's properties. Aggregate, including crushed carbonate rock, is required to have minimum geotechnical qualities before it can be used in asphalt and concrete. In order to reduce chances of premature and expensive repairs, extensive freeze-thaw tests are conducted on potential construction rocks. These tests typically involve 300 freeze-thaw cycles and can take four to five months to complete. Less time consuming tests that (1) predict durability as well as the extended freeze-thaw test or that (2) reduce the number of rocks subject to the extended test, could save considerable amounts of money. Here we use a probabilistic neural network to try and predict durability as determined by the freeze-thaw test using four rock properties measured on 843 limestone samples from the Kansas Department of Transportation. Modified freeze-thaw tests and less time consuming specific gravity (dry), specific gravity (saturated), and modified absorption tests were conducted on each sample. Durability factors of 95 or more as determined from the extensive freeze-thaw tests are viewed as acceptable—rocks with values below 95 are rejected. If only the modified freeze-thaw test is used to predict which rocks are acceptable, about 45% are misclassified. When 421 randomly selected samples and all four standardized and scaled variables were used to train aprobabilistic neural network, the rate of misclassification of 422 independent validation samples dropped to 28%. The network was trained so that each class (group) and each variable had its own coefficient (sigma). In an attempt to reduce errors further, an additional class was added to the training data to predict durability values greater than 84 and less than 98, resulting in only 11% of the samples misclassified. About 43% of the test data was classed by the neural net into the middle group—these rocks should be subject to full freeze-thaw tests. Thus, use of the probabilistic neural network would meanthat the extended test would only need be applied to 43% of the samples, and 11% of the rocks classed as acceptable would fail early.

A redescription of Atopacanthus dentatus Hussakof and Bryant, 1918 (Acanthodii, Ischnacanthidae)

The holotype specimen of the ischnacanthid acanthodian Alopacanthus dentatus comprises most of the posterior half of a dentigerous jaw bone, rather than a fragment from the middle of the jaw as was previously believed. A new diagnosis and revised description for the taxon are based on the holotype from the Rhinestreet Shale (Frasnian) and other specimens front the North Evans and Genundewa limestones (early Frasnian) of the Genesee Formation (late Givetian-early Frasnian); all of: these dentigerous jaw bones were collected near Hamburg, New York state, U.S.A. An emended diagnosis for Atopacanthus clarifies the differences between it and other ischnacanthid genera.

Geochemistry of late Archaean stromatolites from Zimbabwe: evidence for microbial life in restricted epicontinental seas

We report comprehensive trace element and Sr-isotope data for microbial carbonates from the Archaean Mushandike limestone, Masvingo Greenstone Belt, Zimbabwe. The stromatolites have very coherent REE + Y patterns and share the essential shale-normalised characteristics of other Archaean marine precipitates (positive La and Gd anomalies, absence of a negative Cc anomaly and a strongly superchondritic Y/Ho ratio). Mixing models constrain the maximum amount of shale contamination to 0.25-1% and calculated detritus-free carbonate REE + Y systematics require precipitation from seawater. In terms of light-REE over heavy-REE depletion, however, the studied samples are very different from all other known Archaean marine precipitates. In shale-normalised plots, the Mushandike samples yield a negative slope. A very restricted, regional input source of the dissolved load is indicated because normalisation with locally occurring tonalite gneiss REE + Y data yields a pattern closely resembling typical shale-normalised Archaean marine chemical sediments. The disappearance of a negative Eu anomaly when patterns are normalised with local tonalite gneiss strengthens this interpretation. Sr-isotope ratios are strongly correlated with trace element contents and ratios, which explains the modest scatter in Sr-isotope ratios as representing (minor) clastic contamination. Importantly, even the least contaminated samples have very radiogenic initial Sr-87/Sr-86 ratios (0.7184) implying Sr input from an ancient high Rb/Sr source, such as the early Archaean gneisses of south-central Zimbabwe. A local ancient (3.5-3.8 Ga) source is also indicated by previously published Pb-isotope datasets for the Mushandike stromatolites. This is entirely compatible with the occurrence of 3.7-3.8 Ga zircons in quartzites and metapelites from comparably old greenstone belts within less than 150 km of the studied locality. Comparison of the Pb-isotope ratios of the Mushandike stromatolites with 2.7 and 2.6 Ga old stromatolites from the neighbouring, Belingwe Greenstone Belt demonstrates differences in initial isotope composition that relate to the extent of exchange with the open ocean. The development of numerous basins on old continental crust, with water masses variably restricted from the open ocean. suggests a lack of strong vertical topography on this late Archaean craton. (C) 2004 Elsevier B.V. All rights reserved.