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A series of negative gravity anomalies found along the southern part of the Rocky Mountain Trench in Canada is interpreted to be the effect of relatively deep basins in the trench floor. These are apparently filled with light material and are separated from each other by regions of only thin cover over bedrock of normal density. The pattern obtained is very suggestive of a system of longitudinal and transverse faults, and the gravity field is therefore consistent with the theory that the trench, in this vicinity, was produced chiefly by downfaulting.

Grain drying is very specific to the geographic location, kind of drying system, and the type of grain. Under a given set of conditions, the optimal system can be selected based on careful evaluation. However, a good choice of drying systems, procedures, and management practices can be made from the information already available. The review of several grain-drying procedures has provided some insight in making a quick evaluation of the process and arriving at the most suitable system for a particular application. Despite extensive research efforts, the present knowledge of grain drying is yet insufficient to optimally design each drying process with respect to capacity, quality, and energy requirement. There is a need for incorporating grain and air parameters more accurately. It is also important to develop comprehensive drying simulation models to encompass agronomic practices, such as planting and harvesting. Recent efforts indicate a strong influence of planting and harvesting strategies on optimal drying and storage system selection. Results of the varietal trials at Ohio State University indicate that it is now possible to select midseason varieties, which dry down rapidly, without sacrificing yield. Also, low moisture at harvest is important to the energy management process because it affects total drying time and energy required. It is also important from a quality standpoint because kernel damage increases rapidly at harvesting moisture levels above 25%. The trend in grain-dryer design has shifted from focusing on drying capacity and operation reliability to energy consumption. The development in design of energy efficient continuous-flow dryers has been significant. Multistage concurrentflow dryers are excellent examples. Various aspects of dryer staging for efficient operation and control are yet to be determined. Recirculation of the exhaust air is a proven method of improving energy efficiency. Likewise, in batch-in-bin systems, stirring and intermittent drying are worth considering. Further research is required to formulate the best procedures for exhaust air recirculation and intermittent drying. Low temperature drying has a great potential in the U.S. corn belt. The suitability of low temperature drying at other places and for grains other than corn has not yet been well established. Energy savings resulting from low temperature drying entail careful planning and management on the part of the operator. Poor design and operation can result in a serious deterioration in grain quality.(ABSTRACT TRUNCATED AT 400 WORDS)

The hypothesis of multiple crustal plates floating on viscous material, called asthenosphere, provides reason for viewing the earth's outer shell or lithosphere as a dynamic system of shifting continents and changing ocean basins that has shaped world geography during the past 200 m.y. concurrent with the accumulation of roughly 90 percent of the known reserves of oil and gas. Plate tectonics offers a powerful approach to exploring the continental margins (extending offshore to water depths of 15,000 ft or 4,600 m) which reasonably could contain more oil and gas than the land. Relative movements among crustal plates suggest classification of continental margins (as divergent, convergent, and transform), and discussion of their origin in the context of structural style, te perature history, gross stratigraphy (including source, reservoir, and trap potential), and particularly the time and place relation of these factors necessary for oil and gas accumulation. The formation of divergent, Atlantic-type, margins by extension tectonics (including continental rifting, crustal subsidence, and seaward tilting) reasonably encourages exploration because high earth temperatures favorable for generation and expulsion of oil and gas prevail at the same time and place as shallow-water sedimentation (that favors the formation of sources, reservoirs, and traps). Clues to possible oil and gas provinces buried within or beneath thick carbonate platforms or thick land-derived sediment include: fossil rifts or pull-apart basins, peninsula and island split-offs, remnants of tear faults or transverse grabens (aulacogens), reefs, salt or slump-related features, volcanic rocks, and onlap unconformities with stratigraphic pinchouts. Convergent, Pacific-type margins invite exploration in Cenozoic sediments deposited during the formation of several basin types that favor oil and gas generation, expulsion, and accumulation for varied combinations of reasons. These include rapid, deep burial and subsequent uplift by thrust faulting adjacent to oceanic trenches, and high earth temperatures associated with extension faulting in marginal seas of Asian-Pacific margins. Continental collision, representing the final stage of plate convergence, results in extreme contrasts of topography, sedimentation, structure, and oil potential and in realization that understanding the continental margins of the present helps in the understanding of ancient continental margins that now form parts of the land, including most of the known reserves of oil and gas.

ABSTRACT This review of concepts regarding the structural, stratigraphic, and temperature history of continental margins suggests that the prospective offshore area of the world, extending to water depths of 8,000 feet or 2,500 meters reasonably could exceed the prospective onshore area including regions already explored and producing. The formation of continental rifts and divergent (Atlantic type) margins by a real-extension tectonics (including normal and oblique-slip faulting, and divergent triple junctions) encourages exploration in Mesozoic and Cenozoic sediments because high earth temperatures (favorable for generation and explosion of oil and gas) reasonably occur during or soon after shallow-water sedimentation that may form sources, reservoirs and impermeable traps prior to subsidence and burial under younger sediment and deep water. Convergent (Pacific type) margins reasonably include areas of high potential where Cenozoic sedimentation favors the formation of sources, reservoirs, and traps in regions of abnormally high earth temperatures in back-arc basins of the Western Pacific and southeast Asia; and in areas where seafloor spreading axes have encountered Andean subduction trends as in southern California and coastal Peru. The prospectively of subduction thrust-fault trends depends on special circumstances (such as offshore east of Trinidad) where the influx of sediment from the continent provides reservoirs and unruptured traps for oil and gas above distorted older sediments that generally favor oil and gas generation and expulsion. The overwhelming oil and gas reserves of the Middle East and the Soviet Urals suggest that collision margins offer the greatest potential for giant field reserves (greater than 100,000,000 barrels). INTRODUCTION Plate tectonics, the hypothesis of multiple crustal plates floating on viscous material called asthenosphere provides reason for viewing the earth's outer shell or lithosphere as a dynamic system of shifting continents and changing ocean basins that has shaped world geography during the past 200 million years concurrent with the accumulation of roughly 90 percent of known reserves of oil and gas. Although most known reserves of oil and gas occur onshore (under the present land) nearly all the reservoirs have an offshore (marine) origin, implying that the present offshore areas are prospective also. The rudiments of oil and gas accumulation include:a source of unoxidized organic material disseminated in the sedimentary rock sequence;time and heat to change this organic source material to oil and gas;porous and permeable rocks for migration paths and reservoir storage;impermeable (sealed) traps to localize and prevent the escape of oil and gas to the earth's surface, and;the right time and place relationships of items 1 through 4 above. Thickness estimates of unmetamorphosed sediment of the world suggest that offshore oil and gas resources could exceed the onshore resources, including regions already explored and producing. The importance of biotic proliferation and input of land-derived sediment in the formation of reservoirs suggests that nearly all of the offshore resources will be discovered in water depths of less than 8,000 feet, about 2,500 meters.

and mild winter temperatures that allow for year round culture of turfgrass. Local, state, and federal agencies Irrigation scheduling systems which estimate actual evapotranspiracharged with monitoring and/or securing water supplies tion (ETa) by adjusting reference evapotranspiration (ETo) with crop coefficients (Kcs) have been suggested as a means of improving irriga- are particularly concerned about the rapid expansion tion management of turfgrass in the desert southwest. The objective of urban irrigation in the DSW, and there is growing of this study was to develop turfgrass Kcs for use with ETo computed by public pressure to regulate irrigation of turfgrass strictly. the Penman Monteith Equation recommended by the United Nations Scientific irrigation scheduling regimes which compute Food and Agricultural Organization (FAO). Crop coefficients were irrigation water requirements on the basis of estimates developed for fairway quality ‘Tifway’ bermudagrass (Cynodon dac- of actual evapotranspiration (ETa) have been suggested tylon L. C. transvaalinsis Davy) in summer and overseeded ‘Frog- as one means of improving irrigation management of hair’ intermediate ryegrass (Lolium perenne L. multiflorum )i n turfgrass. The required values of ETa are usually obwinter by relating daily measurements of ETa obtained from weighing tained by multiplying estimates of reference ET (ETo) lysimeters to ETo computed with meteorological data. Monthly and computed from meteorological data by a correction facseasonal Kcs were developed by (i) computing the mean of individual daily Kcs, (ii) dividing cumulative ETa by cumulative ETo for the tor known as a crop coefficient (Kc). period, and (iii) computing the slope of least squares regression lines Daily values of ETo are readily available from public relating ETa to ETo. The three computation procedures did not weather networks in the region (Snyder et al., 1985; greatly affect the resulting Kc value. Bermudagrass Kcs ranged from Brown et al., 1988; Mott and Sammis, 1990; Devitt et 0.78 in June to 0.83 in September, with monthly variation related to al., 1992), and many golf courses and parks operate onturf growth rate. Use of a constant Kc of 0.80 would suffice for estimat- site weather stations to provide local ETo data. With ing ETa in summer. Monthly Kcs for intermediate ryegrass ranged this widespread availability of ETo data, access to relifrom 0.78 in January to 0.90 in April and varied in relation to mean able K cs becomes a limiting factor when implementing air temperature. Increased bulk surface resistance resulting from chillscientific irrigation scheduling systems for turfgrass. A induced reductions in stomatal conductance and/or a reduction in turf number of studies have addressed the water requiregrowth rate and leaf area index may lower ETa and Kcs during the

In situ ozone measurements were made from the ER-2 aircraft during the 1987 Airborne Antarctic Ozone Experiment both inside and outside the ozone hole. Midday measurements from late August until late September during aircraft ascent near 53 deg S latitude indicate no clear temporal trend in ozone mixing ratio but instead reflect the distance of the measurement from the chemically perturbed region. The measurements made within the ozone hole at 72 deg S show altitude-dependent decreases in ozone of 61 percent at a potential temperature of 425 K down to 39 percent at 365 K. Temporal trends are also calculated at various positions relative to the boundary of the chemically perturbed region to locate the region of large ozone decreases and thereby accurately locate the boundary of the ozone hole.

Simultaneous in situ measurements of NO, NO2, and O3 were obtained from balloon flights near 50°N in August and December 1982. NOx (NO + NO2) was reduced by a factor of 10 in the 21- to 28-km region in winter. Both NO and NO2 exhibited very sharp vertical gradients in the vicinity of 29 km. NO, for example, increased by nearly 20 times over only a 1-km increase in altitude. By considering air mass trajectories for the time of the winter flight, the reduction in NOx in the lower and middle stratosphere was determined to be consistent with photochemical conversion, principally to N2O5.

Simultaneous in situ measurements of NO, NO2, O3, and temperature were made from approximately 20 to 31 km in the stratosphere during July, August, and November. Two of the balloon flights were made from Palestine, Texas (32°N), the third from Gimli, Manitoba (50°N). NO was detected using the chemiluminescence technique; NO2 was photolyzed to NO prior to detection. Both the NO and NO2 mixing ratios are in good agreement with most other measurements in this altitude region. To within the combined uncertainties the measured NO2 to NO ratios agree with those calculated assuming photochemical steady state. There is, however, a tendency for the observed ratio to be larger than the calculated ratio at low altitudes near 32°N, but not at 50°N. Refinements to the experiment will be required to elucidate unequivocal discrepancies. From the observation of a temporal increase in the sum of NO and NO2 while at constant altitude, it is possible to infer the abundance of N2O5 near noon. Further, a lower-limit estimate of the total odd nitrogen mixing ratio of 16–19 parts per billion by volume near 30 km is made using the observations of NOx, the estimated N2O5 mixing ratio, and previous measurements of HNO3.