Three Kilauea eruptions have produced accessible lava ponds in the pit craters Kilauea Iki (1959). Alae (1963). and Makaopuhi west pit (1965). These have provided a unique laboratory in which to study the cooling and crystallization of basaltic magma. The results of field and laboratory studies conducted at Kilauea place constraints on processes that take place during cooling of shallow magma chambers and of thick basaltic lava flows. Field methods of study include repeated core drilling to determine the thickness of upper crust. collection of gas and measurement of temperature and oxygen fugacity in uncased drill holes. sampling and measurement of viscosity of molten basalt, and periodic measurement of changes in surface altitude and crack configuration. Laboratory studies include measurement of density, chemical composition, and conductivity of drill core, megascopic and microscopic study of crystal and glass content as a function of depth, time, and temperature, and finite-element modeling of the thermal history. Liquidus temperatures of each magma are at or above 1200°C depending on MgO content. Solidus temperatures are all near 980°C. The interface between rigid ‘crust' and fluid ‘melt' occurs at 1070 ± 50°C. The thickness of upper crust in each lake during the first several months increased at a nearly linear rate of 40 cm per unit change in measured in days. Finite-element modeling of the cooling of Alae lava lake has established that cooling is controlled principally by conductive heat transfer. Most measured temperatures there can be computed within 50°C with a model assuming a latent heat of 80 ± 5 cal/gm and a constant diffusivity of .006 cm2/sec and taking into account the heating and vaporization of the measured rainfall of approximately 250 cm/yr. The rainfall considerably hastened post-solidification cooling of the lake. Measured temperatures can be more closely duplicated using a diffusivity based on the measured density and calculated heat content of the lava and on a conductivity that decreases with porosity and increases with temperature. The cooling rate of Makaopuhi and Kilauea Iki may have been increased by convective heat transfer in the melt, as indicated by measured temperature fluctuations and melt differentiation in Makaopuhi. Three kinds of crystal-liquid differentiation are observed in the lava lakes as inferred from chemical analysis of drill core: (1) gravitative settling of olivine phenocrysts, (2) filter-pressing of low-temperature (l030–1070°C) liquids into open fractures, and (3) downward concentration of augite and plagioclase during inferred convective flow. Similar chemical variation observed in Kilauea rift eruptions suggests that these differentiation processes occur on a larger scale within the Kilauea conduits. Some features are unique to each lake. One example is the pattern of vesiculation represented by changes in crust and melt density with depth and by surface altitude changes. Vesiculation is important in determining the density stratification in each lake, and hence the convective history. The distribution of vesicles depends in part on the initial volatile content and on differences in the mode of filling of each lake. These observations made for any single lava lake cannot, therefore, be directly applied to other basaltic lava flows without consideration of evidence for initial gas content and vesiculation history.

s with Program GEOLOGICAL SURVEY CIRCULAR 911

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Lineanents and fracture traces have been mapped throughout Decatur County, Indiana. These lineaments and fracture traces may indicate that solutionenlarged vertical fractures in the limestone and dolonite aquifers underlie most of the county. The use of lineament and fracture-trace maps in selecting bedrock-drilling sites results in a significant increase in the number of usable sites. Bedrock wells drilled on or near mapped lineaments and fracture traces have a higher average yield than veils drilled into interfracture areas. Parts of Decatur County and several adjacent counties are economically restricted by inadequate water supplies. The Greensburg ffanicipal Water Works, supplying 35 percent of the county's population, obtains 25 percent of its water from six wells in Greensburg. The remaining 75 percent is pumped from the Flat Rock River. This water is piped 8.25 miles and lifted 183 feet to the treatment station. Although the Flatrock River has adeduate flow to supply Greensburg's water needs, a ground-water supply can probably be developed nearer the treatment plant. Pleistocene till covers most of the nearly horizontal bedrock. Although averaging about 50 feet thick, this unconsolidated unit does not seem to inhibit the mapping of lineaments and fracture traces. Bedrock is middle Paleozoic limestone, dolomite, and shale. Two sequences of limestone and dolomite, separated by a thin shale unit, constitute the principal aquifer. The extremely variable well yields from this aquifer indicate that the bedrock permeability is also variable. Well placement is important in a fractured bedrock terrane, as fractures are a principal source of water to the well. Here, the most productive bedrock wells are at the mapped intersection of two or more fracture traces or lineaments and at the lowest local altitude. Use of a fracture-trace map will not guarantee a sufficient supply of ground water but will reduce the chance of drilling an inadequate well.

From introduction: The investigation described herein is a part of the USGS Evolution of Sedimentary Basins Program. This report concerns the Pennsylvanian and Permian stratigraphic framework, structural development, and paleogeography of the San Juan Basin.

The goal of the U.S. Global Change Research Program (USGCRP) is to gain an understanding of complex Earth Systems so that change can be predicted and a scientific basis for formulating national and international policy can be established. The USGCRP has three objectives: documenting the Earth’s system through careful coordinated observations; improving scientific understanding of the processes; and developing models that will allow accurate global and regional predictions. Improvements in computer technology, including the use of coupled models, are making it possible to document how the different components of the Earth system work together. With increased understanding of these interactions, capabilities for predicting global change and associated natural hazards will be greatly increased.

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JAWRA Journal of the American Water Resources AssociationVolume 21, Issue 6 p. 901-906 WATER RESOURCES ACTIVITIES OF THE U.S. GEOLOGICAL SURVEY1 Dallas L. Peck, Dallas L. Peck Director, United States Geological Survey, WGS-Mail Stop 121, Reston, Virginia 22092.Search for more papers by this author Dallas L. Peck, Dallas L. Peck Director, United States Geological Survey, WGS-Mail Stop 121, Reston, Virginia 22092.Search for more papers by this author First published: December 1985 https://doi.org/10.1111/j.1752-1688.1985.tb00185.x 1 Paper No. 85185 of the Water Resources Bulletin. Discussions are open until August 1, 1986. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume21, Issue6December 1985Pages 901-906 RelatedInformation