Regional distribution and thickness of post-Palaeozoic sediments on the continental margin of southern Africa

1973 ◽  
Vol 110 (2) ◽  
pp. 97-102 ◽  
Author(s):  
R. V. Dingle

SummaryThe asymmetry of the continental margin around southern Africa can be related to Mesozoic sediment thicknesses, which were in turn controlled by the local structural setting. On the west coast, the Orange Basin sediments were built out as a thick wedge over the margin of the continent by discharge from the Orange River, whereas on the Agulhas Bank, sedimentation was confined to continental areas. Off the east coast the extremely narrow margin of the continent did not form an effective trap for sediments, which were readily carried beyond it. Cainozoic sediments are thin, and modify the Mesozoic sediment pile only locally on the outer shelf and slope.

2008 ◽  
Vol 21 (1) ◽  
pp. 22-39 ◽  
Author(s):  
Siegfried D. Schubert ◽  
Yehui Chang ◽  
Max J. Suarez ◽  
Philip J. Pegion

Abstract In this study the authors examine the impact of El Niño–Southern Oscillation (ENSO) on precipitation events over the continental United States using 49 winters (1949/50–1997/98) of daily precipitation observations and NCEP–NCAR reanalyses. The results are compared with those from an ensemble of nine atmospheric general circulation model (AGCM) simulations forced with observed SST for the same time period. Empirical orthogonal functions (EOFs) of the daily precipitation fields together with compositing techniques are used to identify and characterize the weather systems that dominate the winter precipitation variability. The time series of the principal components (PCs) associated with the leading EOFs are analyzed using generalized extreme value (GEV) distributions to quantify the impact of ENSO on the intensity of extreme precipitation events. The six leading EOFs of the observations are associated with major winter storm systems and account for more than 50% of the daily precipitation variability along the West Coast and over much of the eastern part of the country. Two of the leading EOFs (designated GC for Gulf Coast and EC for East Coast) together represent cyclones that develop in the Gulf of Mexico and occasionally move and/or redevelop along the East Coast producing large amounts of precipitation over much of the southern and eastern United States. Three of the leading EOFs represent storms that hit different sections of the West Coast (designated SW for Southwest coast, WC for the central West Coast, and NW for northwest coast), while another represents storms that affect the Midwest (designated by MW). The winter maxima of several of the leading PCs are significantly impacted by ENSO such that extreme GC, EC, and SW storms that occur on average only once every 20 years (20-yr storms) would occur on average in half that time under sustained El Niño conditions. In contrast, under La Niña conditions, 20-yr GC and EC storms would occur on average about once in 30 years, while there is little impact of La Niña on the intensity of the SW storms. The leading EOFs from the model simulations and their connections to ENSO are for the most part quite realistic. The model, in particular, does very well in simulating the impact of ENSO on the intensity of EC and GC storms. The main model discrepancies are the lack of SW storms and an overall underestimate of the daily precipitation variance.


PEDIATRICS ◽  
1963 ◽  
Vol 32 (3) ◽  
pp. 319-325
Author(s):  
S. Z. LEVINE

THERE ARE A number of reasons why I appreciate deeply your invitation to join in these dedication exercises of the Clinical Research Center for Premature Infants. This Center for the care and study of premature infants extends to the West Coast a field of study in which I, on the East Coast, have been interested for many years. Equally gratifying is the circumstance that it will have Dr. Norman Kretchmer, my long-time colleague and good friend, as its Principle Investigator; and Dr. Sumner Yaffe, his distinguished associate, as its first Program Director. Under their direction and with a team of competent workers, with splendid facilities and an adequate budget, we are assured of imaginative exploration and new approaches to the many unknowns still awaiting solution.


1972 ◽  
Vol 62 (5) ◽  
pp. 1119-1132 ◽  
Author(s):  
K. L. Kaila ◽  
V. K. Gaur ◽  
Hari Narain

Abstract Using the Kaila and Narain (1971) method, three quantitative seismicity maps have been prepared for the Indian subcontinent which are compared with regional tectonics. These are the A-value map, the b-value map and the return-period map for earthquakes with magnitude 6 and above where A and b are the constants in the cumulative regression curve represented by log N = A - bM. The A-value seismicity map shows that India can be divided into two broad seismic zones, the northern seismically highly active zone and the southern moderately active zone. In the northern active zone, a number of seismic highs have been delineated such as the Pamir high, the northwest-southeast trending Srinagar-Almora high, the Shillong massif high, the Arakan Yoma high and the West Pakistan highs. These seismic highs are consistent with the Himalayan tectonic trends. Contrary to this, two seismic highs fall in the Tibet plateau region which align transversely to the main Himalayan trend. In the southern moderately active zone, two seismic highs are clearly discernible, the east and the west coast high, the latter being seismically more active than the former. The least active zone encompasses the Vindhyan syncline and the areas of Delhi and Aravalli folding. Between this zone and the east coast high lies another moderately active zone which encloses the Godavari graben, western part of the Mahanadi graben and the Chattisgarh depression. The b-value seismicity map also demarcates the same active zones as are brought out on the A-value map. The return-period map of India for earthquakes with magnitude 6 and above shows a minimum return period of 100 years in the Pamirs, about 130 years in the various seismic highs in the northern active zone, 180 years on the west coast high, 200 years on the east coast high and about 230 years in the least active Vindhyan-Aravalli zone and the Hyderabad-Kurnool area. These quantitative seismicity maps are also compared with the seismic zoning map of Indian Standards Institution and seismicity maps of India prepared by other workers.


Author(s):  
Susan A. MacManus ◽  
David J. Bonanza ◽  
Anthony A. Cilluffo

This chapter examines the critical political geography of Florida—the 130-mile expanse from Tampa on the west coast to Daytona Beach on the east coast known as the I-4 corridor.This mix of urban, suburban, and rural counties usually decides elections in Florida.


Bothalia ◽  
1987 ◽  
Vol 17 (2) ◽  
pp. 191-194 ◽  
Author(s):  
G. E. Gibbs Russell

The Villosa species group in the genus  Ehrharta Thunb. is differentiated morphologically by very large, profusely hairy, bearded and aristate spikelets and by a suffrutescent habit, with culms woody at the base and with reduced leaf blades. The Villosa group is composed of two species, one with a variety: E. thunbergii Gibbs Russell, nom. nov., E. villosa Schult. f. var.  villosa and E. villosa var. maxima Stapf. Members of the group occur on sandy soils in the Succulent Karoo and Fynbos Biomes, along the west coast in Strandveld and on the southern coast as far east as the Fish River. Morphologically, the group appears to be related to the Calycina and Capensis groups.


Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 517-525 ◽  
Author(s):  
D Gallagher ◽  
E J McGee ◽  
P I Mitchell

Data on radiocarbon (14C), 137Cs, 210Pb, and 241Am levels in an ombrotrophic peat sequence from a montane site on the east coast of Ireland are compared with data from a similar sequence at an Atlantic peatland site on the west coast. The 14C profiles from the west and east coasts show a broadly similar pattern. Levels increase from 100 pMC or less in the deepest horizons examined, to peak values at the west and east coast sites of 117 ± 0.6 pMC and 132 ± 0.7 pMC, respectively (corresponding to maximal fallout from nuclear weapons testing around 1964), thereafter diminishing to levels of 110–113 pMC near the surface. Significantly, peak levels at the east coast site are considerably higher than corresponding levels at the west coast site, though both are lower than reported peak values for continental regions. The possibility of significant 14C enrichment at the east coast site due to past discharges from nuclear installations in the UK seems unlikely. The 210Pbex inventory at the east coast site (6500 Bq m−2) is significantly higher than at the west coast (5300 Bq m−2) and is consistent with the difference in rainfall at the two sites. Finally, 137Cs and 241Am inventories at the east coast site also exceed those at the west coast site by similar proportions (east:west ratio of approximately 1:1.2).


1989 ◽  
Vol 40 (1) ◽  
pp. 1 ◽  
Author(s):  
JR Ovenden ◽  
AJ Smolenski ◽  
RWG White

The orange roughy, Hoplostethus atlanticus, forms the basis of an important trawl fishery in Australia and New Zealand which is currently being over-exploited. To gain information about the stock structure of an Australian orange roughy population, ten restriction enzymes were used to survey the restriction- site variation in the mitochondrial genome of 23 individuals collected from the east coast and 26 individuals collected from the west coast of Tasmania. The mean diversity between all 49 genomes was a low 0.19%. Of the eleven haplotypes identified, only one was present in both the east and west coast samples. Four haplotypes were found only in the east coast sample and six were found only in the west coast sample. Eight haplotypes were related to the haplotype found on both coasts by the gain or loss of one restriction site. One haplotype collected in the east coast sample was related to one other east coast haplotype by one site change. One haplotype collected from the west coast was related to a west coast haplotype by one site change. If this pattern is confirmed by further mitochondrial DNA studies, it could be inferred that gene flow between the orange roughy populations on the east and west coasts of Tasmania is low.


2010 ◽  
Vol 10 (3) ◽  
pp. 36-50 ◽  
Author(s):  
Philip Davenport

This is a response to Towards Harmonisation of the Construction Industry Security of Payment Legislation: A consideration of the success afforded by the East and West Coast Models in Australia by Jeremy Coggins, Robert Fenwick Elliott and Matthew Bell. Towards Harmonisation is based upon the false premise that the objectives of the East Coast and West Coast models are the same. They are chalk and cheese. Each serves a valuable purpose. Each jurisdiction needs both models.  A model for a dual process incorporating both the East Coast and the West Coast models will be found in Davenport (2007).


2020 ◽  
Vol 91 (6) ◽  
pp. 3444-3453
Author(s):  
Catherine D. de Groot-Hedlin

Abstract Seismic T waves, which result from transformation of hydroacoustic to seismic energy at coastlines, were investigated for two strong earthquakes. A 2014 Caribbean event generated seismic T waves that were detected at over 250 seismometers along the east coast of the U.S., primarily at seismic stations operated by the USArray Transportable Array. A 2006 Hawaiian event generated seismic T waves observed at over 100 seismometers along the west coast. Seismic T-wave propagation was treated as locally 2D where the incoming hydroacoustic wavefronts were nearly parallel to the coastlines. Along the east coast, seismic T-wave propagation velocities were consistent with surface waves and a polarization analysis indicated that they were transverse waves, supporting their interpretation as Love waves. They were observed at inland distances up to 1134 km from the east coast. Along the west coast, the propagation velocity was over 5  km/s and a polarization analysis confirmed that the seismic T waves propagated as seismic P waves. Differences between the modes of propagation along the east and west coasts are attributed to differences in the slope and thickness of the sediment coverage at the continental slopes where hydroacoustic to seismic conversion takes place.


Sign in / Sign up

Export Citation Format

Share Document