Northwest Half Research Articles

Reorganization of Snowfall beneath Cloud Top within the Comma Head Region of Two Extreme U.S. East Coast Winter Cyclones

Abstract This paper examines ice particle reorganization by three-dimensional horizontal kinematic flows within the comma head regions of two U.S. East Coast winter storms and the effect of reorganization on particle concentrations within snowbands in each storm. In these simplified experiments, the kinematic flows are from the initialization of the HRRR model. Ice particles falling through the comma head were started from either 9-, 8-, or 7-km altitude, spaced every 200 m, and were transported north or northwest, arriving within the north or northwest half of the primary snowband in each storm. The greatest particle concentration enhancement within each band was a factor of 2.32–3.84 for the 16–17 December 2020 storm and 1.76–2.32 for the 29–30 January 2022 storm. Trajectory analyses for particles originating at 4 km on the southeast side of the comma head beneath the dry slot showed that this region supplied particles to the south side of the band with particle enhancements of factor of 1.36–2.08 for the 16–17 December 2020 storm and 1.04–2.16 for the 29–30 January 2022 storm. Snowfall within the bands had two source regions: 1) on the north/northwestern side, from ice particles falling from the comma head, and 2) on the southeastern side, from particles forming at or below 4-km altitude and transported northwestward by low-level flow off the Atlantic. While the findings give information on the source of particles in the bands, they do not definitively determine the cause of precipitation banding since other factors, such as large-scale ascent and embedded convection, also contribute to snow growth. Significance Statement Wintertime storms along the east coast of North America can produce heavy snowfall, high winds, coastal flooding, and cold temperatures, resulting in major economic impacts within the northeast U.S. urban corridor. The heaviest snowfall typically occurs within snowbands, elongated narrow regions identifiable by high reflectivity on radar. This paper examines the potential sources of the ice particles contributing to the snowbands and how the flow fields throughout the storm can contribute to enhanced particle concentrations within the bands.

Microscopic Identification of 24 Timber Samples Obtained from Half-Timber Walls in Northern Spain—Considerations on the Relationship between Species and Constructive Needs

Traditional architecture characteristically uses locally available materials to develop constructive systems and techniques, providing an optimum response to the needs of the population. This study focuses on half-timber walls as a traditional technique taking material form in a wide range of variants found mostly in the northwest half of Spain. Primarily aiming to ensure the broad objective of in-depth documentation, understanding, and study, the microscopic analysis of 24 timber samples obtained from different half-timber walls is proposed. This analysis aims to identify the species or species groups used and to establish a correlation with different aspects of construction including structural resistance, durability, and workability. This makes it possible to identify the predominant use of species found close to the locations from which the samples are obtained, using relatively resistant species for the structural elements of the half-timber wall, as well as the use of species with flexible and easily malleable branches for the construction of the enclosure panels. This indicates that, among the species available in a given location, builders have a degree of knowledge on the characteristics of the material, so they could choose the most suitable ones or develop specific constructive solutions based on these characteristics.

Inter-provincial responsibility allocation of carbon emission in China to coordinate regional development.

To establish the carbon emission trading scheme and achieve the carbon emission reduction goals in China, it is critical to allocate the carbon emission allowance (CEA). Using the entropy method and the modified fixed cost allocation model (MFCAM), we calculated the CEA and the carbon emission intensity (CEI) reduction targets of 30 Chinese provinces in 2030, from four principles (equity-efficiency-feasibility-sustainability) and three dimensions (economy-society-environment). The results are shown as follows. First, China's total carbon emissions in 2030 calculated in this paper are 17567.9 Mt. Second, on the whole, CEA in China's southeast half of the Hu line is higher than that in the northwest half. Eastern China has a larger final CEA than western China and central China. Third, Henan, Guangdong, Shandong, and Jiangsu are the four provinces with the most CEA, while Gansu, Qinghai, Ningxia, and Hainan are the four regions with the least carbon allowances. Fourth, the regions of Shanxi, Shaanxi, Xinjiang, Ningxia, Inner Mongolia, Guizhou, and Anhui will take on greater responsibility for carbon reduction in the future. On the contrary, the zones of Tianjin, Qinghai, Guangxi, Jilin, Yunnan, and Beijing will be able to sell CEA in the future. Fifth, provinces are divided into three categories from the perspective of CEI reduction. Finally, we put forward relevant policy recommendations based on the conclusions.

Spatially Resolved RGS Analysis of Kepler’s Supernova Remnant

Abstract The distribution and kinematics of the circumstellar medium (CSM) around a supernova remnant (SNR) tell us useful information about the explosion of its natal supernova (SN). Kepler's SNR, the remnant of SN 1604, is widely regarded to be of Type Ia origin. Its shock is moving through a dense, asymmetric CSM. The presence of this dense gas suggests that its parent progenitor system consisted of a white dwarf and an asymptotic giant branch (AGB) star. In this paper, we analyze a new and long observation with the reflection grating spectrometers on board the XMM-Newton satellite, spatially resolving the remnant emission in the cross-dispersion direction. We find that the CSM component is blueshifted with velocities in the general range 0–500 km s−1. We also derive information on the central bar structure and find that the northwest half is blueshifted, while the southeast half is redshifted. Our result is consistent with a picture proposed by previous studies, in which a “runaway” AGB star moved to the north-northwest and toward us in the line of sight, although it is acceptable for both single- and core-degenerate scenarios for the progenitor system.

Changes of Spatiotemporal Pattern and Network Characteristic in Population Flow under COVID-19 Epidemic

The COVID-19 pandemic is a major problem facing humanity throughout the world. The rapid and accurate tracking of population flows may therefore be epidemiologically informative. This paper adopts a massive amount of daily population flow data (from January 10 to March 15, 2020) for China obtained from the Baidu Migration platform to analyze the changes of the spatiotemporal patterns and network characteristics in population flow during the pre-outbreak period, outbreak period, and post-peak period. The results show that (1) for temporal characteristics of population flow, the total population flow varies greatly between the three periods, with an overall trend of the pre-outbreak period flow > the post-peak period flow > the outbreak period flow. Impacted by the lockdown measures, the population flow in various provinces plunged drastically and remained low until the post-peak period, at which time it gradually increased. (2) For the spatial pattern, the pattern of population flow is divided by the geographic demarcation line known as the Hu (Heihe-Tengchong) Line, with a high-density interconnected network in the southeast half and a low-density serial-connection network in the northwest half. During the outbreak period, Wuhan city appeared as a hollow region in the population flow network; during the post-peak period, the population flow increased gradually, but it was mainly focused on intra-provincial flow. (3) For the network characteristic changes, during the outbreak period, the gap in the network status between cities at different administrative levels narrowed significantly. Thus, the feasibility of Baidu migration data, comparison with non-epidemic periods, and optimal implications are discussed. This paper mainly described the difference and specific information under non-normal situation compared with existing results under a normal situation, and analyzed the impact mechanism, which can provide a reference for local governments to make policy recommendations for economic recovery in the future under the epidemic period.

The distribution of Chinese minority populations and its change based on the study of the Hu Huanyong line

The “Hu Line” and its demographic implications have attracted world-wide attention since the line was developed 80 years. Using GIS, this paper conducts a statistical analysis and systematic investigation on the stability and spatial of China’s minority population growth on both sides of “Hu Line” by constructing the spatial database of China’s census data from 1953 to 2010 and initiating a new method for identifying the spatial patterns of population growth. Major findings are as follows: (1) Spatial distribution of the minority population in China is not balanced, showing a significant spatial clustering; (2) The minority population is widely distributed across China, spreading to East China and all over the country; (3) The distribution pattern of China’s minority population is characterized by extraordinary stability, with the ratio of south-east half to north-west half standing roughly at 75:25 from 1953 to 2010. We can thus say that the “Hu Line” is also a mutant line of China’s minority population.

China’s different spatial patterns of population growth based on the “Hu Line”

The “Hu Line” has been regarded as one of the greatest geographical discoveries in China because it reveals the significant spatial relationship between human activity and natural environment. The spatial evolution of population on both sides of the “Hu Line” has had important implications for both urbanization and regional development and has attracted widespread attention during the dramatic economic and social changes since the implementation of reform and opening-up policy in China in 1978. Using Geographical Information System (GIS) techniques, this paper studied the stability of the “Hu Line” and the spatial patterns of population growth on each side by constructing a spatial database of China’s census data from 1982 to 2010. The findings are as follows: (1) In the last 30 years, the “Hu Line” has remained relatively stable, but a new tendency of population change has begun to emerge. The population ratio either side, namely, the southeast half (SEH) and the northwest half (NWH), of the “Hu Line” remains at roughly 94:6 (SHE: NWH). Noteworthy, the proportion of population in the SEH of the “Hu Line” has been decreasing slightly, while that in the NWH has been increasing slightly, as the latter has benefited from its higher rate of natural population growth. (2) The spatial patterns of population growth on both sides of the “Hu Line” were quite different. The degree of population concentration in the SEH increased faster than the NWH. Regions with a negative population growth rate have rapidly expanded; these were mainly located in the south of the “Qinling Mountains-Huaihe River belt” and northeastern China. Meanwhile, regions with a fast population growth rate were mainly concentrated in the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin metropolitan area. Thus, the spatial pattern of population growth in the SEH presented a concentration pattern that could be called “Matthew effect pattern”. (3) The spatial pattern of population growth in the NWH could be regarded as the “Relative Balance pattern.” In the NWH, the population growth rate was positive and the degree of population concentration was very low. There were many minority populations located in the NWH that usually lived in a dispersed pattern but had a higher rate of natural population growth due to the preferential population policy. There were also some regions with a negative rate of population growth in the NWH, which were mainly located close to the “Hu Line” and the Ancient Silk Road. (4) In the future, the spatial patterns of population growth on both sides of the “Hu Line” may continue to evolve. For the SEH, the capacity to attract more people to small and medium-sized cities and towns should be enhanced. For the NWH, the emphasis should be placed on promoting urbanization and enhancing population agglomeration in its major cities.

Abundance, distribution and habitat characteristics of winter skate Leucoraja ocellata in the southern Gulf of St Lawrence: a population on the brink of extirpation?

Abundance indices of southern Gulf Leucoraja ocellata residing in Northumberland Strait, Canada, declined from 2001 to 2005, but increased during 2006 to 2008. Catch rates in 2009 were the lowest in the time series. The size of the area occupied in Northumberland Strait varied with changes in the abundance indices. Leucoraja ocellata were primarily caught in the north-west half of the strait over sandy to gravelly seabed; a near total absence was documented from the eastern half despite suitable habitat and a previously established presence documented during research surveys conducted before 2000. In Northumberland Strait, L. ocellata occupied shallow (50% cumulative occurrence = 12 m) and warm (50% cumulative occurrence = 16·5° C) coastal waters and were not present in the cold (<1° C, >35 m) intermediate layer. Abundance and distribution data highlight the need for continuing studies to monitor the status of this population, which is classified as endangered by the IUCN and Committee on the Status of Endangered Wildlife in Canada.

Carbon Star Survey in the Local Group. VI. The Dwarf Spheroidal Galaxy NGC 205

We present a CFH12K survey of the carbon stars in NGC 205 and its surrounding field. We find that the number of C stars in NGC 205 is low (~500) for its luminosity and that very few C stars are seen outside of the 10' isophote, suggesting tidal stripping by M31. Their MI = -4.54, a magnitude nearly identical to what has been found in other galaxies with numerous C stars. Stars with accurate (R-I) photometry, to I ≈ 22.5, are used to determine the outer profile of NGC 205. A King profile with rt = 1977 ± 300 fits the data for distances larger than 7'. This rt implies that NGC 205 reached a minimum distance to M31 of ~42 kpc. The spatial distribution of C stars in the surrounding field reveals that some C stars belong to to the disk of M31, seen in projection, and that a surplus of C stars seen west of NGC 205 could be part of tidal debris left along its orbit. Finally, we report evidence of a transient period of enhanced star formation that occurred 1–2 Gyr ago in the northwest half of NGC 205.

Long-distance longitudinal transport of gravel across the Cordilleran thrust belt of Montana and Idaho

Two newly identified middle Eocene paleovalleys (≥ 100 km long) preserved on top of the southwest Montana reentrant of the Cordilleran fold-and-thrust belt indicate long-lived longitudinal flow across the thrust belt and resolve a long-standing debate about the source of the voluminous quartzite debris in the Upper Cretaceous to lower Tertiary Divide, Harebell, and Pinyon conglomerates of Montana, Idaho, and Wyoming. Geologic mapping, stratigraphic, provenance, and geochronologic studies revealed that Eocene volcanic and sedimentary rocks in the paleovalleys are as thick as 2 km, onlap preexisting bedrock, and interfinger with well-rounded conglomerate derived from formations exposed only to the west. The middle Eocene paleovalleys are the youngest expression of a major paleoriver system that transported sediment toward the foreland during the Sevier orogeny. An Eocene subcrop map shows that the headwaters of the Eocene paleovalleys coincided with structural culminations in the thrust belt that supplied sediment to the Divide conglomerate of the Upper Cretaceous to lower Tertiary Beaverhead Group. Ultimately, the Lemhi Pass and Hawley Creek paleovalleys provided several thousand cubic kilometers of quartzite debris to the Pinyon and Harebell conglomerates of northwest Wyoming 200–350 km away, and formed the northwest half of a giant longitudinal drainage system. Sevier contraction, not the rising Idaho batholith, first uplifted vast culminations beneath the headwaters of this river system.

Spiess Ridge: An axial high on the slow spreading Southwest Indian Ridge

We report recent mapping of Spiess Ridge with the Hawaii‐MR1 sidescan sonar. Spiess Ridge is an unusual elongate 90 by 50 km volcanic feature on the slow spreading Southwest Indian Ridge near the Bouvet hotspot. The northwest half of the ridge has a narrow ∼7‐km neovolcanic zone in MR1 sonar images and a simple magnetic anomaly sequence including possible anomalies C1n and C2n. In contrast, the southeast half shows extrusive volcanism over &gt;40 km with distributed eruption sites, a broadened central magnetic anomaly with no anomaly C2n, and a volcanic ridge radiating from the summit of Spiess Ridge, oblique to the spreading orthogonal trend. The images show no evidence for large‐offset normal faults or an axial rift valley typical of slow spreading ridges. Overall, Spiess Ridge has an appearance very unlike that of either fast or slow spreading ridges and more transitional between a spreading ridge and a seamount. We compare the morphology of Spiess Ridge to other large volcanic structures in oceanic rifts. Spiess Ridge and Bouvet Island represent localized zones of excess melting along the Southwest Indian Ridge and we discuss their origin in the light of current ideas on ridge‐hotspot interaction.

Facies analysis of an ancient, dismembered, large caldera complex and implications for intra-arc subsidence: Middle Jurassic strata of Cobre Ridge, southern Arizona, USA

The Middle Jurassic (∼ 170 Ma) Cobre Ridge caldera is an elongate caldera complex that formed during the eruption of the tuff of Pajarito, a crystal-rich rhyodacite ignimbrite with an estimated volume > 1000 km 3. The caldera subsided in two subequal blocks: to the southeast, caldera-forming ignimbrite is as much as 3000 m thick, whereas the northwest half of the caldera subsided to lesser depths during the initial eruption, but was the locus of subsidence during subsequent eruptions, providing a depocenter for a > 1.5 km-thick section of secondary- and post-collapse volcanic and sedimentary strata. These strata record moat formation and filling and waning volcanism, including: (1) areally restricted ignimbrites up to several tens of meters thick that may have been ponded between caldera margins and/or fault scarps; (2) a ⩾ 600 m-thick ignimbrite whose eruption probably caused further collapse of the caldera or enlargement of the caldera margins; (3) a localized debris apron deposit up to 500 m thick that represents material reworked from intra-caldera pyroclastic deposits and possibly caldera walls; and (4) eolian and fluvial sandstones and water-lain tuffs. Megabreccia blocks as large as 0.5 km along strike probably demarcate approximate caldera margins, suggesting that the composite caldera was approximately 50 km long by 25 km wide. The preserved thickness of the strata of Cobre Ridge ( > 4500 m) is greater than many ancient continental volcanic sequences, suggesting external (i.e. tectonic) controls on subsidence, but preservation of this great thickness of strata is apparently due entirely to volcanic subsidence.

The Medina Wrench: a key to the kinematics of the central and eastern Mediterranean over the past 5 Ma

The Medina Wrenth in the central Mediterranean is a transform fault connecting the plate collision in northwest Africa and northern Sicily with that occurring at the Aegean plate boundary, south of Greece. The more than 800 km long crescent-shaped wrench zone is currently seismically quiet but exhibits major deformation since 5 Ma within a belt 30–100 km wide. It forms the southern boundary of two microplates moving eastward with respect to Africa and Europe. A simple plate rotation model constrained by recent paleomagnetic data indicates that a continental Iblean microplate and a hybrid continental/oceanic Ionian microplate, separated along the Malta Escarpment, have rotated anticlockwise by 11° and 12°, respectively, around poles in southern Italy. These rotations involved some 100 km of dextral eastward movement relative to Africa of the Ionian Basin north of the Medina Wrench since 5 Ma. Combining the published 26° clockwise rotation of the Peloponnesus and northwest half of the Aegean with the 12° anticlockwise rotation of the Ionian microplate results in (a) a 99% agreement between the length of the seismic Benioff Zone beneath Greece and the total convergence of the microplates, and (b) an average rate of convergence across the Aegean plate boundary southwest of the Peloponnesus of 6.6 ± 1cm a −1 since the Miocene. Relative motion between microplates in a collision zone thus may be as much as 6 times faster than convergence between the major plates which spawned them, and they can be considered rigid to the first order over the time span involved.

Geology of the peralkaline volcano at Pantelleria, Strait of Sicily

Situated in a submerged continental rift, Pantelleria is a volcanic island with a subaerial eruptive history longer than 300 Ka. Its eruptive behavior, edifice morphologies, and complex, multiunit geologic history are representative of strongly peralkaline centers. It is dominated by the 6-km-wide Cinque Denti caldera, which formed ca. 45 Ka ago during eruption of the Green Tuff, a strongly rheomorphic unit zoned from pantellerite to trachyte and consisting of falls, surges, and pyroclastic flows. Soon after collapse, trachyte lava flows from an intracaldera central vent built a broad cone that compensated isostatically for the volume of the caldera and nearly filled it. Progressive chemical evolution of the chamber between 45 and 18 Ka ago is recorded in the increasing peralkalinity of the youngest lava of the intracaldera trachyte cone and the few lavas erupted northwest of the caldera. Beginning about 18 Ka ago, inflation of the chamber opened old ring fractures and new radial fractures, along which recently differentiated pantellerite constructed more than 25 pumice cones and shields. Continued uplift raised the northwest half of the intracaldera trachyte cone 275 m, creating the island's present summit, Montagna Grande, by trapdoor uplift. Pantellerite erupted along the trapdoor faults and their hingeline, forming numerous pumice cones and agglutinate sheets as well as five lava domes. Degassing and drawdown of the upper pantelleritic part of a compositionally and thermally stratified magma chamber during this 18-3-Ka episode led to entrainment of subjacent, crystal-rich, pantelleritic trachyte magma as crenulate inclusions. Progressive mixing between host and inclusions resulted in a secular decrease in the degree of evolution of the 0.82 km3 of magma erupted during the episode.

High-velocity, asymmetric Doppler shifts of the X-ray emission lines of Cassiopeia A

view Abstract Citations (68) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-velocity, asymmetric doppler shifts of the X-ray emission lines of Cassiopea A. Markert, T. H. ; Canizares, C. R. ; Clark, G. W. ; Winkler, P. F. Abstract Using the Focal Plane Crystal Spectrometer on the Einstein Observatory, we have performed high spectral resolution measurements of several X-ray emission lines from the young supernova remnant Cassiopeia A. The spectrum of the X-ray emitting gas in the northwest half of Cas A is redshifted with respect to that in the southeast. We interpret this phenomenon as a Doppler shift and find the mean velocity difference between the two regions to be 1820 ± 290 km s-1. Within each region the breadth of the X-ray lines implies a Doppler broadening of ∼5000km s-1 (FWHM). These measurements demonstrate directly that the bulk of the gas making up Cas A is moving at high velocities. We have constructed a simple geometric model consistent with the general features of the X-ray spectrum and image of Cas A-a broad ring of matter inclined to the line of sight. The data constrain the parameters of the model and in particular require an expansion velocity in excess of 2000 km s-1. The high velocities required for the X-ray matter (and the consequently high temperature of the primary shock) imply that the relatively cool X-ray emitting material that we observe is most probably supernova ejecta which has been heated by a reverse shock wave. Although alternative scenarios cannot be excluded, the X-ray and optical data are most compatible with the view that Cas A is still in its free-expansion stage. We find that the X-ray emitting mass is probably ≳10 Msun as previously determined by others, and the kinetic energy is ∼4 × 1051 ergs. The spatial and Doppler asymmetries may be caused by modest inhomogeneities either in the distribution of circumsource material or in the ejecta themselves, as has been suggested for rapidly rotating massive stars. Publication: The Astrophysical Journal Pub Date: May 1983 DOI: 10.1086/160939 Bibcode: 1983ApJ...268..134M Keywords: Cassiopeia A; Doppler Effect; Emission Spectra; Line Spectra; Supernova Remnants; X Ray Sources; Abundance; Astronomical Models; Astronomical Spectroscopy; High Resolution; High Speed; Red Shift; Spectral Line Width; Spectral Resolution; Stellar Mass Ejection; X Ray Spectra; Astrophysics full text sources ADS |

Nested calderas and trapdoor uplift at Pantelleria, Strait of Sicily

Pantelleria is dominated by a caldera 6 km in diameter that formed 55,000 yr ago during eruption of a rheomorphic fall deposit that is zoned from pantellerite to trachyte. Trachytic lavas then built a shield that nearly filled the caldera. Magma subsequently reinflated the shallow reservoir and raised the northwest half of the trachyte shield 275 m, creating Montagna Grande by trapdoor uplift. The lid eventually failed, and pantellerite magma erupted as domes, flows, and pumice cones along the trapdoor faults and their hingeline. We have identified a second caldera ∼93,000 yr old, within which the younger caldera is nested; a still-older structure may encircle them both. Replenishment of magma reservoirs beneath calderas can promote dilatant reactivation of older subsidence structures, resulting in multicyclic collapses that reuse these structures and produce nested calderas.

On the Planimetric Shape of Wreck Bay, Vancouver Is.

ABSTRACT The planimetric shape of Wreck Bay has been studied by fitting various segments of the bay to theoretical logarithmic spiral curves, and by using the characteristics of incident swell to estimate longshore sediment transport along the beach. We have found that the cliff base in the northwest half of the bay closely follows log-spiral curvature, whereas the southeast half reflects only poor correspondence. This situation is due largely to distortion of the incident swell by two islands in the bay, Florencia Is., and Seal Rock. Quasi-permanent cliff sections supporting large trees occur on the landward side of the theoretical log-spiral curves, and those sections exposing unconsolidated glaciofluvial outwash are generally seaward of the curves. Present day erosion, due mainly to wind action on the exposed parts of the cliff, indicates that gradual mutation of the planimetric shape, particularly for the southeast half of the bay, is tending towards an improved fit. Longshore current distribution along the beach accounts for the direction of spit-bar growth at the mouth of Lost Shoe Creek, and also for the presence of Sand Point in the middle of the bay. It has been found useful when comparing the goodness of fit of beaches of different lengths to introduce a normalized root mean squared error. Furthermore, it has been shown that if a headland remains part of a receding spiral beach, then the spiral center must gradually migrate away from the headland as erosion proceeds.

Reflection profiling in and around the Puerto Rico Trench

Continuous seismic reflection profiles were recorded across the Dominican trench (south of Puerto Rico and Hispaniola), the Puerto Rico trench, and the outer ridge. These profiles show details of the structure in the upper layers which could not be measured by the refraction techniques heretofore employed. In the Caribbean there are several layers (unconsolidated and consolidated sediments) which dip northward as though the crust were depressed by the weight of the island ridge. A very small abyssal plain in the Dominican trench suggests either a relatively recent date for the deformation or the absence of a good source of turbidity current sediments with access to the trench. The measurements in the Puerto Rico trench strongly suggest that the north wall is a fault scarp or a series of parallel fault scarps. Along a traverse extending 120 miles north from the shelf of Puerto Rico, the sediments are thin, ranging in thickness from zero to about 200 meters except under the narrow trench abyssal plain. Distortion of the sediments in the bottom of the trench suggests that they have tilted downward toward the south during deposition. The total accumulation of sediment is remarkably small. The measurements on the outer ridge show up to 1 km of low-velocity sediments, except in the region just north of the trench where there is some question of interpretation of the records. In some areas the sediments are markedly distorted, probably indicative of post-depositional tectonic activity. Along a traverse (SH-2B) extending about 200 miles northeast from 21°25′N, 69°50′W, near Silver Bank, the average thickness of sediments approaches 1 km. The southwest half of this traverse crosses an abyssal plain beneath which the sediments show stratification of a type hitherto found by us only near continents. The northwest half shows less stratification and a rough surface, apparently resulting from post-depositional deformation.

A Method of Drilling in Deep Water

Abstract The waning supplies of domestic petroleum make it desirable to develop oilfields in new provinces, among the most attractive of which appear to besubmarine deposits; notably, in the Great Lakes. The author's portable openfoundations and means of oil-field development are presented. His designs for30 to 100 ft. of water, and for 100 to 600 ft., which offer possibilities ofcompletely exploiting the continental shelves, are set forth. It is emphasizedthat foundations must be of sufficiently low cost to be attractive. A methodfor overcoming ice hazards is outlined. Introduction New sources of petroleum and natural gas are beneath large bodies of watersuch as the Great Lakes, except Lake Superior, and ultimately the continentalshelves. It is now particularly desirable to exploit the Great Lakes because:there is an acute shortage of petroleum and natural gas in the surroundingarea;the Lakes are far inland and safe from enemy raidersthey offerthe shallowest possible sources remaining in this countrythe water isnot as rough as in the open seas. The one discouraging condition, floating ice in the winter, should offer noproblem. In the Great Lakes, four places appear attractive for prospecting for oil:the western end of Lake Eriethe northwest half of Saginaw Baythe east side of Lake Michigan between Benton Harbor and Ludingtontheshallow south end of Lake Huron. The title to submerged lands beneath navigable waters of the United Statesis owned by the various states. The boundaries are established. Leasing wouldhave to be from the states, but before mineral could be extracted, approvalmust be obtained from the War Department. Methods of Development The shallower parts of such small bodies of water as the western end of LakeErie, Lake St. Clair or Saginaw Bay, could be prospected and drilled by thesubmersible barge of Giliasso, one of which can keep a single string of toolsrunning for about eight months of the year. Some of the deepest wells have beendrilled from submersible barges in the bays and bayous of the Gulf Coast. TheCedar Point field in Galveston Bay was developed by barge drilling. This methodat present is limited to water less than 10 ft. deep, and is not suitable inopen water like that offshore in the Gulf of Mexico or the Pacific Ocean. T.P. 1722