Geophysical and remote-sensing methods were applied to better understand sinkhole precursor movement and assess the potential for sinkhole development in evaporitic areas. The approach is illustrated with two examples over bedded salt deposits and a salt dome in Texas, USA. Large sinkholes (90 to 200 m in diameter) formed over Permian bedded salt near Wink in western Texas in June 1980 and May 2002, and on the flank of a coastal-plain salt dome in Daisetta in May 2008. Residents, government officials, and industry representatives wish to better understand the potential for sinkhole formation and growth in both areas. At Wink, limited spatial and temporal data on vertical ground movement from standard surveying has been greatly extended by satellite-based radar interferometry, which was used to delineate areas having recent movement and determine rates of movement. Results from interferometry guided site-specific investigations that included acquisition of high-resolution gravity data, which identified shallow-source mass deficits that indicate potential for continued subsidence or sinkhole formation. At Daisetta, interferometry was used to determine that no detectable subsidence preceded sinkhole collapse (indicating sudden collapse once the upward-migrating void reached a depth that allowed the cohesiveness of overlying semiconsolidated sediments to be overcome), and gravimetry was used to identify other areas where shallow mass deficits exist across the salt dome. Data from both areas can be used to construct risk maps, design comprehensive subsurface investigations, and develop monitoring programs based on repeat radar interferometry and geodetic GPS measurements.

The Hueco bolson of Trans-Pecos Texas formed in response to Cenozoic extensional tectonism and lies within the southern Rio Grande rift near the poorly defined boundary between the rift and the southern Basin and Range province. The bolson is composed of a northwest subbasin that contains north-striking normal faults and a southeast subbasin that contains northwest-striking normal faults. Cenozoic basin fill is thin (less than 150 to 200 m) on the east and northeast bolson margins and is thick (as much as 2,850 m) in the central bolson and on the west and southwest bolson margins where major normal faults bound a graben that is 15 to 25 km wide. Major faults bounding the graben on the west and southwest have been more active and exhibit greater offset than do boundary faults on the east. This disparity in displacement between the graben margins has resulted in an asymmetric graben. Isopach maps of lower and upper basin fill sequences, differentiated from seismic data, indicate that much of the southeast Hueco bolson subsided more than the northwest Hueco bolson during deposition of the lower basin fill. Thicker upper basin fill within the northwest basin indicates that the basin subsided more in the northwest than in the southeast during deposition of the upper basin fill.The two major faults that bound the Hueco graben on the west and southwest, the East Franklin Mountains fault and Amargosa fault, respectively, have had the most recent (late Pleistocene-Holocene) surface ruptures. Scarp-slope angles of these faults are commonly steeper than 20°, and middle Pleistocene surficial deposits that contain indurated calcic soils having stage IV to V morphology are offset between 24 and 32 m. Maximum throw on these faults during single surface-rupture events has been between 1.6 and 3 m. Major faults bounding the southeast Hueco graben on the northeast (Campo Grande, Caballo, and an unnamed fault) had their most recent surface ruptures during the late Pleistocene. Scarp-slope angles of these faults are rarely as much as 15° and more commonly between 4 and 7°. Middle Pleistocene surficial deposits that contain indurated calcic soils having a stage IV to V morphology are offset between 1.6 and 24 m. Maximum throw on these faults during single surface-rupture events has been between 0.6 and 2 m.

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In this study, 445 patients under 19 years of age who visited an urban hospital emergency facility for acute illnesses four or more times over 2 years were randomly divided into two groups. The parents of 230 of the patients received three letters that stressed the value of continuous pediatric care and the lack of continuity available in emergency facilities. The letters indicated a willingness to offer advice as to how they could obtain continuing care. The remaining 215 patients served as controls. During the following year, the patients whose parents received the letters and the controls were compared in their visits to the hospital's emergency facility, primary care unit, and subspecialty clinics. Very few differences were noted between the two groups.

SUMMARY 17 cases of neonatal death dwarfism are reported. They include Majewski syndrome, Meckel syndrome, Homozygous Achondroplasia, Rhizo‐melic type of Punctate Epiphyseal Dysplasia, Cloverleaf Skull syndrome, Lethal form of Osteo‐genesis Imperfecta, Campomelic Dwarfism and Achondrogenesis syndromes. The authors believe that there are four well differentiated types of Achondrogenesis which can be recognised on x‐ray examination alone. These are Achondrogenesis I as reported by Parenti31 and Fraccaro4, Achondrogenesis II as delineated by Goard and Kozlowski5 as “Thana‐tophoric Dwarfism II”, and Achondrogenesis III as reported by Hams et al.8 as “Pseudoachondro‐genesis with Fractures”. Three cases of neonatal death dwarfism — two of them familial — with some distinct features are reported and a tentative designation of Achondrogenesis IV is proposed. The authors regard as unlikely the possibility that Achondrogenesis IV may represent different stages or a variant of Achondrogenesis I, II or III. In every case of neonatal death dwarfism, photographs, radiographs, biochemical, histological and histochemical studies should be performed. This may help to classify this group of diseases and finally establish the causative biochemical defect.

We combined multifrequency airborne electromagnetic induction (EM) measurements of apparent ground conductivity with chemical analyses of surface water to delineate natural and oilfield salinity sources that degrade surface water quality by elevating total dissolved solids, chloride and sulphate concentrations along several hundred kilometres of the Colorado River (western Texas, USA). To reduce the cost of airborne geophysical surveying over such large areas, we used a helicopter to tow an EM instrument at low altitude along the stream‐axis and measure the apparent electrical conductivity of the ground at multiple frequencies, examined results in the field to identify salinized stream segments and optimal water sampling locations and then flew more detailed surveys over these limited areas rather than over the entire basin as is typical in salinization studies. Minimally processed stream‐axis EM data (including apparent conductivities measured at single frequencies and multifrequency ‘spectrograms’ along the stream‐axis) helped identify salinized streambed segments, discriminate between surface and subsurface sources of salinity and determine water sampling locations upstream and downstream from each segment. We integrated EM, streamflow and hydrochemical data to calculate salinity loads, identify specific natural and oilfield salinity sources and guide and implement remediation efforts. Stream‐axis flight lines offer the advantage of rapidly acquiring high‐resolution subsurface conductivity data along long stream segments where traditional gridded flight‐line surveys and waterborne measurements are impractical or prohibitively expensive. They also overcome difficulties associated with topographic effects when surveying deeply incised streams. Such surveys provide valuable information on location, extent and type of salinization and can guide water sampling and more intensive ground or airborne measurements.

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