The Chromite Deposits of Stillwater and Sweetgrass Counties, Montana

In writing this report, two objects were kept in mind, (1) to explain, if possible, the origin of the chromite deposits found in Sweetgrass and Stillwater Counties, and (2) to bring up to date all information on these deposits which had thus far been available. The work done consisted of study of the rocks and ores of the area under the microscope, both as thin sections and as polished sections, practically all of which was done at the Montana State School of Mines, during the school year of 1928 - 1929. The rock specimens and much information as to their locations and probable compositions were obtained from Mr. P. F. Minister, of the East Butte Copper Company. United States Geological Survey Bulletin 725-A, Deposits of Chromite in California, Oregon, Washington, and Montana, and the unpublished report on the Chromite deposits of the Boulder River, prepared by Prof. C. H. Clapp of the University of Montana, were frequently referred to and considerable material was drawn from them. The map of the Boulder River area is from Clapp's report.

Some Early Geologists and Their Work in Montana

This paper marks an increased refinement and more detailed accuracy in the description of the geological features of the state. It includes the recent studies of mineral deposits, of oil structures, of the formations of bedded rocks and their included fossils, carried on both by the Federal and State governments and by various interested private persons, such as the mining companies. It is within this period that the Federal Government encouraged the U. S. Geological Survey in the publication of monographs on the National Parks, papers of great popular interest and educational value making these beautiful regions comprehensible in their geological features to the touring public.

Impact of environmental regulations on lead concentrations in Texas ambient air and water: 1970--1990

In the last two decades, the significance of lead has been addressed in a number of environmental regulations at the national and state levels. This project investigated the environmental regulations (Clean Air Act and Amendments, 1970-1990 and Clean Water Act of 1977) and their cumulative effects on lead in ambient air and water in the state of Texas. For this purpose, historical records from the Texas Water Development Board, Texas Natural Resources Conservation Commission, and the United States Geological Survey have been assembled and analyzed for temporal and spatial trends. These trends might correspond to the phase out of lead in gasoline and other regulations.^ This study concluded that there is a significant correlation (p $\leq$.001) between environmental regulations of lead in gasoline and the concentration of lead in ambient air. Lead concentrations in ambient air have been reduced by over 90 percent in the past twenty years. An overall significant difference (p $\leq$.001) was found in mean (94, 15 respectively) lead concentrations in surface water between two time periods, one at the beginning of the twenty year period and one at the end of the study period. There has been an overall reduction of lead concentrations in surface water in Texas of approximately 84 percent. However, this reduction cannot be statistically associated with any one regulation. Groundwater data could not be analyzed for lead concentrations because of limitations of reporting data as "less than". Approximately two percent of the groundwater data was analyzed by Oneway ANOVA and no significant difference was found between the means (18, 19 respectively) of two time periods, 1977-1979 and 1988-1990. This data is consistent with the regulations having a contributory affect on declining concentrations, but other factors cannot be ruled out as having added to these declines. This study can also serve as a starting point for a more in-depth study of environmental regulations and their impact on the environment. ^

Ground-penetrating radar (GPR) point measurements of ice thickness in Austria

Glacier thickness is an important factor in the course of glacier retreat in a warming climate. Thiese study data presents the results (point data) of GPR surveys on 66 Austrian mountain glaciers carried out between 1995 and 2014. The glacier areas range from 0.001 to 18.4 km**2, and their ice thickness has been surveyed with an average density of 36 points/km**2 . The glacier areas and surface elevations refer to the second Austrian glacier inventory (mapped between 1996 and 2002). According to the glacier state recorded in the second glacier inventory, the 64 glaciers cover an area of 223.3±3.6 km**3. Maps of glacier thickness have been calculated by Fischer and Kuhn (2013) with a mean thickness of 50±3 m and contain an glacier volume of 11.9±1.1 km**3. The mean maximum ice thickness is 119±5 m. The ice thickness measurements have been carried out with the transmitter of Narod and Clarke (1994) combined with restively loaded dipole antennas (Wu and King, 1965; Rose and Vickers, 1974) at central wavelengths of 6.5 (30 m antenna length) and 4.0 MHz (50 m antenna length). The signal was recorded trace by trace with an oscilloscope. 168 m/µs as used by Haeberli et al. (1982), Bauder (2001), and Narod and Clarke (1994), the signal velocity in air is assumed to be 300 m/µs. Details on the method can be are found in Fischer and Kuhn (2013), as well as Span et al. (2005) and Fischer et al. (2007).