The American whale oil industry: A look back to the future of the American petroleum industry?

The American whaling industry rose from humble beginnings off Long island to become an international giant. In its peak year, 1846, 735 ships and 70,000 people served the industry. As whale stocks and reserves decreased, whalers were forced to go farther and farther from their New England home ports. Voyages became longer, and risks on required return-on-investment became higher. The easy money of Atlantic and Pacific whaling was no more: the only remaining profitable ventures were to Arctic and Antarctic waters. Many ships returned empty, if at all. in 1871, most of the Arctic whaling fleet was crushed by early winter ice and lost. This calamity, in conjunction with the long-term diminishing whale stocks, the diversion of investment capital to more profitable ventures, and the discovery, development, and refinement of abundant petroleum crude oil, struck the death blow to the American whaling industry. By 1890, only 200 whaling vessels were at work, and by 1971, no American commercial whaling ship sailed the world's oceans.It is apparent that no single event caused the final, rapid decline. However, a single calamity, in an already stressed industry, that was self-insured and commercially interlinked, precipitated the end. Today's American petroleum industry, although adopting some principles of the American whaling industry, also has embraced other activities such as work process reengineering and customer alliances, which may preempt, or postpone, a similar catastrophic demise.     

The origin of polygonal troughs on the Northern Plains of Mars

Viking photographs have revealed extraordinary systems of crudely polygonal troughs in three different areas of the northern plains of Mars. Trough widths average 200–800 m and average trough spacing is 5–10 km. The widest troughs have flat floors and steep sides which suggest that they are either grabens or tension cracks which have been partially filled. The following three arguments support the garben interpretation: (1) Two clear examples of vertical offsets along trough walls indicate that the troughs formed by downdropping of the floors. (2) Troughs similar in scale and morphology to those of the Martian northern plains form concentric and radial patterns in the Caloris Basin on Mercury. Most likely, they are extensional fractures or grabens resulting from uplift of the basin floor (Strom et al., 1975). The Caloris analogy suggests that the troughs on Mars are similar tectonic features related either to uplift or expansion of the planet. Fourteen rose diagrams of trough azimuths in southeastern Acidalia Planita show that locally they exhibit preferred orientations roughly parallel to the topographic contours, but overall there is no strong regional pattern. (3) The scale of tension crack systems is limited by the depth of fracturing because the extent of stress relief perpendicular to a crack is proportional to the crack depth. Observations of terrestrial tension cracks suggest a lower limit on crack depths of about one-tenth of the average spacing. Thus, if the Martian troughs are tension cracks, they would be expected to have depths of at least 500–1000 m. Mechanical considerations indicate that it is difficult to generate such deep cracks by surficial tension due to thermal cooling and contraction in permafrost, desiccation, or cooling of lava flows. Deep-seated tension of tectonic origin generally results in normal faults and not tension cracks.     

Saturn's rings: Particle composition and size distribution as constrained by observations at microwave wavelengths: II. Radio interferometric observations

The sizes, composition, and number of particles comprising the rings of Saturn may be meaningfully constrained by a combination of radar- and radio-astronomical observations. In a previous paper, we have discussed constraints obtained from radar observations. In this paper, we discuss the constraints imposed by complementary “passive” radio observations at similar wavelengths. First, we present theoretical models of the brightness of Saturn's rings at microwave wavelengths (0.34–21.0 cm), including both intrinsic ring emission and diffuse scattering by the rings of the planetary emission. The models are accurate simulations of the behavior of realistic ring particles and are parameterized only by particle composition and size distribution, and ring optical depth. Second, we have reanalyzed several previously existing sets of interferometric observations of the Saturn system at 0.83-, 3.71-, 6.0-, 11.1-, and 21.0-cm wavelengths. These observations all have spatial resolution sufficient to resolve the rings and planetary disk, and most have resolution sufficient to resolve the ring-occulted region of the disk as well. Using our ring models and a realistic model of the planetary brightness distribution, we are able to establish improved constraints on the properties of the rings. In particular, we find that: (a) the maximum optical depth in the rings is ～ 1.5 ± 0.3 referred to visible wavelengths; (b) a significant decrease in ring optical depth from λ3.7 to λ21.0 cm allows us to rule out the possibility that more than ～30% of the cross section of the rings is composed of particles larger than a meter or so; this assertion is essentially independent of uncertainties in particle adsorption coefficient; and (c) the ring particles cannot be primarily of silicate composition, independently of particle size, and the particles cannot be primarily smaller than ～0.1 cm, independently of composition.     

Microcraters formed in hot glass by hypervelocity projectiles

Microcraters were formed in heated soda-lime glass by the normal incidence of spheres of plastic or fused silica with diameters between 0.8 and 4.5m and velocities between 2.5 and 10 km s^–1. The morphology of the craters in targets at temperatures up to 800°C is little different from those formed in unheated glass. Spallation still occurs to the same extent and above the same velocity threshold, but the spalls sag and sharp edges become dull in a few seconds at temperatures above the softening point. There is a small increase in the flow of glass from the central pit into a narrow lip at the higher temperatures, but this lip is often removed by spallation, especially at the higher velocities of impact. There is no evidence of a splashed lip with strings of melt overlying the spalled area. The results in conjunction with other evidence suggest that most lunar craters of micrometer size with a smooth central pit, splashed lip, and a spallation zone are the result of primary impacts.     

The spectral reflectivity of select areas on Europa

The July 12, 1973, occultation of Europa by Io was observed in 30 wavelength channels in the spectral region λλ3200-11, 000 Å with the 200-inch Hale telescope and a multichannel spectrometer. The data are presented in absolute units above the Earth's atmosphere. The data are analyzed to obtain the spectral reflectivity of seven localized areas on the disk of Europa centered on 324°W longitude. The equatorial material is confirmed to be darker than the eastward-skewed bright north polar cap and a hint is evident that the darker material as well may be somewhat redder than the cap material.     

Distribution and morphology of sinkholes triggered by flooding following Tropical Storm Alberto at Albany, Georgia, USA

Flooding of the Flint River in July 1994 triggered the collapse of at least 312 sinkholes in the karstic Dougherty Plain at Albany, Georgia. We examined the distribution and morphology of these new sinkholes to evaluate the mode of formation, to characterize early stages of the evolution of sinkhole form, and to estimate the lowering of the surface associated with the development of new sinkholes.Eighty-eight percent of sinkholes occur inside the limits of flooding, especially in areas of sandy overburden, and they often follow joint-controlled linear trends. Sinkhole dimensions are log-normally distributed with median values of circumference = 5.7 m, length = 1.8 m, width = 1.6 m, and depth = 0.7 m; asymmetry (L:W) = 1.2. Cross-sectional forms range from narrow cylinders to large bowls, with many sinkholes having undercut sides.Flooding triggered the formation of sinkholes by saturating and liquefying overburden, which caused soil arches to collapse and flow into cavities in bedrock. The prevalence of sinkholes near the periphery of flooding suggests that drainage and loss of buoyant support as flood waters subsided may also have contributed to failure. A volume ratio index is used to quantify the three dimensional geometric form of sinkholes. Initially, small cylindrical shafts open over a bedrock joint, followed by progressive slumping that leads to widening and increases in volume to a final bowl form. Estimates of the aggregate volume of overburden transported underground in flooded areas range from 7,990 to 11,130 m3. Averaged over flooded areas, this accounts for 0.26 to 0.37 mm/km² lowering of the surface. Based on a 500 year recurrence interval for the flood event, values for lowering of the surface range from 0.52 to 0.74 mm per 1,000 years. These values are an order of magnitude less than estimates of carbonate dissolution and suggest that transport of overburden underground is limited by triggering events.