Gulf Province Research Articles

Geophysical Structures and Late Neogene History of Gulf and Peninsular Province of the Californias: ABSTRACT

Researchers from the Continental Margins Study Group at Oregon State University, the Direccion General de Oceanografia, and CICESE have completed a 10-year reconnaissance-scale geophysical survey of the Pacific Exclusive Economic Zone of Mexico. Six cruises, aboard research vessels of the Armada de Mexico, have been completed, and approximately 50,000 nmi of survey track lines have been run. From these data and from other published sources, the authors have compiled a series of onshore-offshore maps of the region extending 1500 nmi from Point Conception in southern Alta California to Lazaro Cardenas in Michoacan. These maps include: Physiography, with 200-m contours of bathymetry and topography; Free-Air Gravity Anomalies, with 10-mgal contours of both onshore and offshore gravity: Marine Magnetic Anomalies and Oceanic Crustal Isochrons, with 50-nT contours over continental crust and 1-m.y. isochrons over oceanic crust; Seismo-Tectonics, with 1963-1982 WWSSN seismicity superimposed on interpreted onshore-offshore faults. Slow gulf rifting, at least in the south, began as early as about 12-14 Ma. Oceanic crust was first exposed there by about 9-10 Ma. Pacific-North American relative motion was distributed between faults in the gulf and faults on the Pacific side of Baja California until about 4-5 Ma. This rifting history is consistent with themore » history of changes in volcanic chemistry along the gulf side of Baja. Initial rifting in the southern gulf was diffuse, involving many small, independently active crustal blocks. Present-day faulting, onshore in northern Baja, in the northern and central gulf, and onshore in Jalisco and Colima, also involves many small, independently active fault blocks and slices that are similar to those occurring onshore in southern Alta California.« less

Urban Movement and Rural Identity: A Papua new Guinea Example

This paper examines how out-migration to town affects the sense of identity among villagers who stay using a Kukipi village in the Gulf province in Papua New Guinea in 1978-1979 as a case study. Apart from a participant observation income data were collected every month for a year from 39 of the 65 households that made up the community. Net outward movement among the Kukipi has greatly altered the location of close relatives and other kin. Nowadays the closest kin of many Kukipi live in town. It is less satisfying to be the parent of an absent son or daughter than of one who resides in the village. A few regularly receive large transfers but many parents are sent far less and not nearly as much as expected. Parents with children in town cannot go to them and ask for food or assistance. The village itself remains an important point of reference for Kukipi and that importance may even have been enhanced by the incidence of migration. Being a Kukipi is now associated more with genealogical descent and less with birthplace. Migration has affected rural Kukipi life styles in terms both of practice and aspirations. Rice flour sugar and tea are consumed every day in the village; there are radios drinking glasses pressure lamps houses made of permanent materials and outboard motors. Sizeable differences in household incomes mean that village life styles can vary greatly between neighbors and even close kin. Village Kukipi do not receive everything they desire. Such broad expectations lead to negative perceptions of their community and in many cases of individual life styles. They see themselves as poor and disadvantaged. To the Kukipi the essence of the good life is food that is sufficient in quantity and quality on both grounds they feel discontented.

Tapping practices and SAP yields of the NIPA palm ( NIPA Fruticans) in Papua New Guinea

Methods of tapping the nipa palm ( Nipa fruticans Wurmb.) were developed in the course of a 3-year study conducted in seven villages in the Baimuru district of the Gulf Province of Papua New Guinea. The experimental sites were located about 1.5–23 km from the sea. Their plant density varied from 4700 to 2400 palms per ha and the mean height of the plants was nearly 13 m. Five pre-treatment patterns were tested. Once-a-week treatment, maintained for 12 weeks, yielded an average of 155 ml of sap/24 h/palm for one month, whereas 3–5-times-a-week treatment, for 5–12 weeks, yielded an average of 1300 ml of sap. The duration of treatment depended on the state of development of the flower stalk. The pre-treatment pattern chosen as the standard was to bend the stalk 12 times in one direction, to pat with the hands the length of the stalk backwards and forwards 64 times, and to give the base four kicks; this was repeated four times a week. In the course of the 3-year study it was found that the average sugar content of fresh nipa sap is rather high, about 16.4% w/v, as compared with, for example, about 12% w/v of sugar cane. The results of the present study are discussed with reference to producing fuel alcohol from the Papua New Guinea nipa palm.

Sources of Pleistocene and Holocene Sand for Northeast Gulf of Mexico Shelf and Mississippi Fan: ABSTRACT

Grain shape, surface texture, and mineralogic analyses were conducted on the Pleistocene and Holocene sands of the northeast Gulf of Mexico shelf and the Mississippi fan to determine their sources. Two distinct petrologic provinces of sand are present in this area: the Mississippi province, characterized by spherical quartz grains derived from older strata in the drainage basin of the Mississippi River, and the eastern Gulf province, characterized by a mixture of spherical and elongate quartz grains. The former is derived from Cretaceous and Tertiary coastal plain strata; the latter is derived from sedimentary and crystalline rocks of the southern Appalachian Mountains. Sand distribution patterns of these two provinces on the northeast shelf are distinct; Mississippi province sands are found in the western part of the shelf near the Mississippi delta, while Eastern Gulf province sands are found throughout the remaining parts of the shelf. However, sands of the Mississippi fan are a mixture of Mississippi and Eastern Gulf province sand. Glacial sand is uncommon in both the Holocene and Pleistocene deposits of the Mississippi province. End_of_Article - Last_Page 1427------------

Future Petroleum Exploration Trends in Arabian Gulf Area: ABSTRACT

The Arabian Gulf Province has more than half the world's discovered oil. The undiscovered potential is perhaps equal to the oil already discovered, and includes enormous quantities of gas. This mature basin is not thoroughly evaluated; it will be carefully reappraised for its full potential. Future exploration and drilling should concentrate on the following: (1) deep unexplored Paleozoic rocks (prolific gas play in Permian Khuff and Cambro-Ordovician rocks on known structures); (2) extension of present pay zones to adjacent areas, and exploration for non-giant structures associated with the giant fields; (3) exploration for stratigraphic and other subtle traps by analysis of geologic data and special seismic processing and interpretation; (4) enhanced recovery from produ ing fields and of shallow heavy oil and low-grade deposits; (5) development of Oligocene-Miocene reservoirs in northern Gulf and Zagros areas for the discovery of new giant fields; (6) development of new geologic-sedimentologic concepts to evaluate source rocks, migration mechanism, reservoirs, and traps; (7) exchange of geologic, geophysical, and geochemical data among Arab countries, and regional petroleum exploration; (8) exploration in the vast areas of the Arabian basin that are not sufficiently tested (Rub al Khali and southern Iraq); (9) better production schemes, based on reservoir and simulation studies and advanced well logs and their evaluation; (10) evaluation of all horizons in presently producing structures; (11) exploration for new oil and gas reserves offshore in the Arab an Gulf; (12) production from fields with high potential that are sealed for economic and market reasons (i.e., the reserves are not commercial by area standards); and (13) exploration in the offshore area of the Arabian Peninsula on the Indian Ocean, which has barely been explored. Future exploration will necessarily involve extensive drilling programs, and the risk of drilling dry holes will be relatively higher. End_of_Article - Last_Page 542------------

Sources, Distribution, and Mixing of Late Pleistocene and Holocene Sands on the South Texas Continental Shelf

ABSTRACT Gross grain shape and mineralogical analyses were used to determine the source, distribution, and mixing of late Pleistocene and Holocene sands on the South Texas continental shelf. Two major gross grain-shape types are found to be present in varying proportions in the sands of this shelf. The first sand type is associated with sands which are relatively enriched in plutonic-metamorphic quartz, volcanic quartz, feldspar and igneous and metamorphic rock fragments, and thus is considered to represent first-cycle sands derived from the Llano Uplift and the silicic volcanic rocks of the Southwest U.S. The second sand type is associated with more quartzose sands rich in sedimentary quartz and sedimentary rock fragments, and is considered to represent multicyclic sands eroded from the Texas Coastal Plain and High Plains. Variations in the relative proportions of these sand types in the sands of the nearshore/inner shelf region reflect both the changing sources of the sand and their transport, mixing, and convergence by modern nearshore processes. Three distinct sedimentary petrologic provinces, corresponding to three provinces previously defined by heavy mineral analysis (Van Andel and Poole 1960), are defined herein on the basis of their relative content of first- and multicyclic sand. Modern sands of the first of these provinces, the Rio Grande, are derived from the drainage basin of the Rio Grande and characteristically contain high proportions of first-cycle sand; such sands are presently found in the nearshore/inner shelf region between the mouth of the Rio Grande and the 27°N latitude to the north of the mouth of the river. Modern sands of the second province, the Texas Coast, are derived largely from the drainage basins of the South Texas coastal plain rivers and characteristically contain high proportions of multicyclic sand; such sands are presently transported southwestward by longshore currents to the 27°N latitude, where they converge with the northward-transported sands of the Rio Grande Province. Modern sands of the third province, the Western Gulf, are derived from the drainage basins of the Colorado and Brazos rivers and characteristically contain high proportions of first-cycle sands', such sands are also transported by longshore currents towards the southwest, where they are gradually diluted by Texas Coast Province sands. Sands of these three provinces are also found in the relict late Pleistocene fluvial and deltaic sediments on the outer part of the South Texas shelf. Previous studies had considered the fluvial and deltaic sediments on the northern part of the shelf to be entirely derived from the Western Gulf Province; however, this study shows that the relict fluvial deposits of certain South Texas coastal plain rivers which occur on the northern part of the shelf should be assigned to the Texas Coast Province. In all, multicyclic sands constitute approximately 48% of the late Pleistocene and Holocene sand of the South Texas continental shelf.

Prehistoric Sites from the Kikori Region, Papua New Guinea

This report presents the findings of excavations and surface site collections conducted by Sandra Bowdler in 1971/72 and by myself In 1976 in the region neighbouring Klkorl Station, Gulf Province (Fig.l). The archaeological surveys from which this information was derived were exploratory and site discovery was by and large guided by area inhabitants, who maintain a knowledge of ancestral village localities. As these factors constrain the rigour with which regional prehistory may be addressed, I limit my attention to descriptive analyses. Thus the results are organised so as to establish a referential data base for future research.

Notes on the Ownership and Utilization of Sago, and on Social Change, among the Moveave‐Toaripi of the Papuan Gulf

Between September and October, 1977, I conducted an ethnobotanical survey at two different places in the Gulf Province of Papua New Guinea. The first was Moveave village situated near the confluence of the Tauri and Lakekamu rivers, East Kerema, and the second Mapaio village located at the fringes of the lower Purari Delta.1 The aim of my research was to locate an ecological area where sago (poi) swamps were of considerable importance in the people's socioeconomic life. Hence, I concentrated, first, on the people's actual knowledge and perception of their own taxonomic system, and also their vernacular nomenclature of sago palms, and, second, on patterns of behaviour related to the division of labour and ownership of sago palms, and on the technology of exploitation and methods of utilization of the sago swamps. The relationship between these aspects and the use of cash raises an issue of some interest.

Developments in Coal in 1982

In 1982, United States mines produced a record high 833 million short tons of coal (about 1% more than in 1981), indicating that a production plateau has been reached. West Virginia's 1982 production increased 16 million tons from that of 1981, Illinois production increased by 12 million tons, and Wyoming production increased 5 million. Although Kentucky decreased in production, it remained the United States leader by producing 150 million tons, followed by West Virginia's 129 million, and Wyoming's 108 million. One-half of the 26 producing states increased production in 1982; the other half decreased production. Illinois showed the greatest rate of increase (19%), Montana the greatest rate of decrease (17%). Regionally, production increased in 5 areas and decreased in 4 areas. In the Eastern Interior it increased 9%, and 5% increases were recorded in both the Rocky Mountain and Gulf Provinces. Ranking first in 1982 was the Appalachian region at 428 million tons of bituminous coal, followed by the Rocky Mountain Province at 175 million tons of bituminous and subbituminous coal, and the Northern Great Plains at 155 million tons of subbituminous and lignitic coal. In 1982, the second highest quantity of coal exported from the United States (106 million tons) was a 6% decline from 1981. This was 13% of 1982 United States coal production; 61% of it was coking coal for use in iron and steel manufacture, and 39% was steam coal used for electric power generation. The European Economic Community, Japan, and Canada received 74.5 million short tons or 70% of these exports in 1982. Coal exploration and mine permits in most producing regions continued at a high level, and federal coal lease sales increased greatly in the Northern Great Plains Province.

Red Bluff, Marion County, Mississippi: A Citronelle Braided-Stream Deposit: ABSTRACT

Red Bluff is an erosional escarpment located on the western margin of the Pearl River flood plain in northwestern Marion County, Mississippi. The bluff shows approximately 30 m (100 ft) of relief and is composed of alternating units of red-to-yellow sand and sandy gravel. The sand grains are composed primarily of quartz, with small amounts of heavy minerals and feldspar. The gravel is composed of varying percentages of chert, flint, jasper, rip-up clasts, quartz, and tripoli, including a small fraction of silicified Paleozoic fossils. Grain-size analysis of the sediment and investigation of the sedimentary structures suggest a braided-fluvial environment of deposition. Particle sizes in the medium sand to pebble range predominate in all units; very little silt and clay is present. The largest particles present are boulder-size rip-up clasts. The most conspicuous sedimentary structures at Red Bluff are graded bedding, low-angle to medium-angle cross-bedding, and well-developed paleochannels. A statistical comparison (discriminant analysis) of the seven most abundant heavy minerals of Red Bluff, with the same suite of heavy minerals found at the type section of the Citronelle Formation (Pliocene-Pleistocene), and outcrops of a known Miocene coarse clastic unit indicates a correlation of Red Bluff to the Citronelle Formation. These heavy minerals are kyanite, staurolite, rutile, tourmaline, zircon, black opaques (primarily ilmenite and magnetite), and white opaques (primarily leucoxene). The suite of heavy minerals present at Red Bluff belongs to the east Gulf province. This metamorphic assemblage of heavy minerals implies the source area of the sediments at Red Bluff to be the southern Appalachians. The silicified pebble-size Devonian-Mississippian fossils were derived most likely from formations flanking the southern Appalachians in northern Alabama. End_of_Article - Last_Page 1472------------

Differentiating Sediments from Different Sources in Gulf Basin by Grain-Shape Analysis: Example from Late Pleistocene-Holocene Sediments of Northwestern Gulf of Mexico Continental Shelf: ABSTRACT

ABSTRACT It has been shown previously that different source rocks produce quartz sand grains with unique gross shape characteristics. These gross shape characteristics cannot be altered by abrasion, and are thus an immutable record of sediment source. Therefore, sand grains in a sedimentary basin should contain in the gross shape a fingerprint of their source unaffected by the amount of reworking to which the sands have been subjected. In order to test this idea, the shapes of late Pleistocene-Holocene sands grains from two sources in the northwest Gulf of Mexico (the Rio Grande and Western Gulf Province) were analyzed with the Fourier grain shape technique. The results indicate that two gross grain shape assemblages are present in the sands of these two provinces. One assemblage is associated with a mineralogical suite typical of relatively mature coastal plain sediments, and thus probably represents the contribution of sediment from such a Coastal Plain Source Terrane. The other assemblage is associated with a relatively immature mineralogical suite more typical of sediments derived from crystalline sources, and thus probably represents the contribution from such a Source Terrane. Both assemblages are found in sands of both provinces, inasmuch as the major rivers in these provinces which act as conduits for these sediments drain both source terrane types. However, the amount of area of these terranes drained by the rivers differs between the provinces, and so the relative proportions of these assemblages in the sands of the two provinces also differ. Rio Grande Province sands contain on the average 59% of the assemblage associated with the Highland Source Terrance, while Western Gulf Province sands contain only 34% of this assemblage. Thus, it is the difference in the relative proportion of these two assemblages in the samples which can be used to identify and distinguish the sands from the two provinces. All in all, the results of this pilot project indicate that the analysis of gross grain shape can indeed differentiate sediments from different sources in the Gulf of Mexico.

From temporary to permanent townsmen: migrants from the Malalaua District, Papua New Guinea.

An attempt is made to explain how a group of people moved from being newcomers to town in the 1940s to being one of the most permanent and stable residential elements in Papua New Guinea's towns in the 1970s. Circular and permanent migration, as Young maintains, are not 2 distinct processes, and both initial rural urban movements and migrants' decisions to return or not to return home are examined simultaneously. The hypothetical career of a migrant is considered all the way from village residence to permanent urban residence along with the different decision points that might vary this career. In this case study focus is on 2 sets of factors that affect migration decisions: an imbalance in rural and urban economic conditions and the effects of the migration process itself. The people discussed come from what is now known as the Malalaua District of the Gulf Province and are referred to as Malalauas. Historically, there are several feastures of Malalaua urban migration that are important. Malalaua migration began earlier than that of most urban migrant groups in Papua New Guinea. In the 1963 urban population there were a number of Malalauas who first came to Port Moresby before or during World War 2. Migration from the Malalaua District has continued in a steady stream from the 1940s to the 1970s, although there is no evidence on absolute numbers of new migrants in any 1 year. The pattern of Malalaua migration to towns over the entire period has been largely one of the movement of young single adult males and young female adults moving to town on marriage. Both the absolute numbers of migrants and the proportion of Malalauas absent from the District have risen rapidly over the 20 years to 1972. Finally, children are being born to Malalaua migrants in town. Malalauas are possibly the migrant group most firmly established in town. The Malalauas are one of the most longterm and residential groups in Port Moresby. In Papua New Guinea as a whole they must be one of the migrant groups with the greatest commitment to urban living. Economic factors have been very important in Malalau decisions to leave the village, particularly the decisions of adult males. The migration process itself has increasingly affected migrant decisions: factors such as the diminished attraction of a depopulated rural community, a change in tastes towards urban based ways of living, the growth of strong personal and family ties among urban residents, and a simultaneous reduction in such ties with rural residents. It is argued that this 2nd set of factors over time increases in importance relative to rural-urban economic imbalance as an explanation of migration behavior. In general, rural urban economic opportunities have become less important over time. So in the 1970s and 1980s it would be argued that many Malalauas would not respond to increases in urban unemployment of rural incomes by moving back to the village. They would be permanent townspeople. This explanation of migration decisions is dynamic: in the history of individuals and groups the context and thus the explanation of decisions change.

Serogenetic Studies on the Kamea (Kapau) Anga of the Interior of the Gulf Province of Papua

Though the Anga or Kukukuku of Papua New Guinea have been the subjects of occasional human biological investigations in the past, these have all been directed from the north, and their largest division, the Kamea or Kapau, who occupy the southeastern half of their territory, have been substantially neglected. The present paper describes the results of sero-genetic investigations of a small sample of Kamea, who are shown to resemble their fellow-Anga closely in the distribution of their genetic markers, though there are indications that the Kamea have received some gene flow from the south. On the whole, though, the relative uniformity of gene marker distribution throughout the Anga points strongly to their common origin, and the paucity of signs of immigrant gene flow from their neighbours, the victims of their raids, tends to confirm that they practised cannibalism rather than the genetic incorporation of captives.

Hydraulic differentiation of heavy minerals, offshore Alabama and Mississippi: Summary

Heavy minerals in the coastal zone of Alabama and Mississippi have been observed for many years; most published work has been either on a broad regional basis (Goldstein, 1942; Hsu, 1960; Shepard, 1960; van Andel and Poole, 1960) or concentrated on the barrier islands (Foxworth and others, 1962; Hahn, 1962; Harding, 1960). The Alabama-Mississippi region lies in the Eastern Gulf Province (Goldstein, 1942), which is characterized, by the metamorphic heavy minerals kyanite, staurolite, tourmaline, and epidote. Goldstein, from 20 samples, suggested an average heavy mineral content of about 0.4 weight percent of the sediment throughout the Eastern Gulf Province. There are few data pertaining to the sub-sea-level mineral distribution in the present area of investigation. Studies by Goldstein (1942), Hsu (1960), and Upshaw and others (1966) have included about a dozen samples from the area. More extensive studies of heavy mineral distributions, transportation, and concentration processes have been undertaken by Tanner and others (1961) and Stapor (1973) for the Apalachicola Bay area of Florida. Stow and others (1976) published preliminary observations on the heavy mineral resource potential for offshore Alabama and Mississippi, but they did not interpret the distribution data.

Subduction and Oil Migration

Petroleum and natural gas pools are abundant within the thick prisms of sediment deposited along many rifted continental margins. Where crustal collisions that assemble composite continents occur, the rifted-margin sediment prisms are drawn down against and beneath the suture belts thus formed. During such partial subduction, fluid hydrocarbons may be driven updip away from the subduction zones to accumulate in reservoirs along adjacent platform margins and within growing foreland fold-thrust belts. The immense petroleum accumulations of the Persian Gulf province southwest of the Zagros suture belt may owe their origin to this process. Similar oil migration in response to partial subduction may have influenced the distribution of petroleum in foreland basins generally; if so, strategies for exploration can perhaps be improved by taking this factor into account.

Heavy Minerals and Size Analysis of the Citronelle Formation of the Gulf Coastal Plain

ABSTRACT The heavy minerals of the Citronelle Formation and fluviatile terraces of Louisiana were examined to determine the source of these sediments. Examination of samples indicates that an East Gulf Province heavy mineral suite (kyanite, staurolite, zircon, tourmaline), typical of the Cretaceous and Tertiary sediments of the Gulf Coastal Province is present throughout the Citronelle and older Louisiana terrace deposits. A Mississippi River province suite (epidote, dolomite, amphibole-pyroxene, garnet), presumably derived from the glacial deposits of the northern United States, is present in the younger Louisiana terrace deposits: the Holloway Praire, Port Hickey, and Irene. Based on previous work and heavy mineral and mechanical analysis data determined in this report, the Citronelle Formation appears to represent an alluvial apron formed by coalescing, braiding streams, in response to epeirogenic uplift of the continental interior during Late Pliocene to preglacial Pleistocene time. Encisement of the Mississippi River and other streams into Citronelle sediments has resulted in entrenched valleys containing fluviatile terraces which are mineralogically and lithologically similar to the Citronelle but are at lower elevations. Younger terrace deposits bearing a Mississippi River province heavy mineral suite are believed to have formed in response to fluctuating sea level during the Pleistocene.

Paleoclimatic Significance of Bryozoan Metrarabdotos: ABSTRACT

The cheilostome bryozoan genus Metrarabdotos occurs abundantly in late Eocene to Recent sediments in the Gulf and Atlantic coastal provinces, the Caribbean region, Europe, and northern and western Africa. The tropical distribution of Recent populations is apparently a consequence of a temperature tolerance of 61° to 82°F. This stenothermy and the distinctive generic morphology of fossil and Recent species provide a basis for identifying tropical faunal provinces on the sublittoral margins of both sides of the Atlantic during late Paleogene and Neogene times. The northern limit of the genus, congruent in Recent seas with the 70°F. isocryme for surface water, has fluctuated during late Paleogene and Neogene times. The amplitude of latitudinal fluctuation has been 8° in the New World and 34° in Eurafrica. The synchronous latitudinal shifts of this line on both sides of the Atlantic probably reflect variations in Atlantic marine climate. The northern boundary of the genus lay at 31° N. Lat. in the Gulf and Atlantic Coastal Plain and at 40°-48° N. Lat. in Europe from late Paleogene to middle Miocene, at about 26° in America and 28° in Europe in late Miocene, and at its northern maximum of 34° in America and 51° in Europe in the Pliocene; it now lies at 29° in the Gulf of Mexico and at 17 76; in Africa. The greater amplitude in Eurafrica is probably the result of a surface-current gyre similar to the modern one. The pattern of increasing amplitude of fluctuation does not agree with a paleo-climatic model of cooling from early to late Tertiary time. End_of_Article - Last_Page 2163------------

Sources of Recent Sediments in the Northern Gulf of Mexico

ABSTRACT Sand-size sediments are contributed to the northern Gulf of Mexico by a large number of streams and, to a lesser extent, by marine erosion of coastal deposits, mainly of Pleistocene age. The heavy mineral assemblages and distributive provinces of most sources can be recognized in the Holocene sediments of the northern Gulf of Mexico. Five heavy mineral provinces have been established, the Eastern Gulf, Mississippi, Western Gulf, Texas Coast, and Rio Grande provinces. The Western Gulf province is of complex origin and consists of sediments deposited on the continental shelf during the early Holocene rise in sea level by the Mississippi, Rio Grande, Colorado, Brazos, and Trinity-Neches Rivers. The changing pattern of alluvial plains, deltas, shore deposits, and several major changes in he direction of longshore drift and currents during the transgression can be recognized. The Texas Coast province consists of a mixture of material contributed by the rivers of the area and of detritus eroded from the Pleistocene deposits of the area by waves. Longshore drift to the west is an agent in the distribution of sediments derived from the Colorado River in the zone between Galveston Bay and Aransas Pass. This material enters the bays from the Gulf side. Barrier island and bay sands are of local origin west of Aransas Pass and consist of a mixture of material derived from the Pleistocene on the land side and material brought in from the shelf during and after the transgression.

Sedimentary Petrologic Provinces of the Northern Gulf of Mexico

ABSTRACT Sediment samples from the northern border of the Gulf of Mexico show regional differences in mineral composition which permit the distinction of four areas of sediments, each with a characteristic mineral suite. These sedimentary petrologic provinces are here termed the Eastern Gulf Province, the Mississippi River Province, the Western Gulf Province, and the Rio Grande Province. The mineral assemblage characteristic of each province is briefly described.

Analysis of Midway Fauna of Western Gulf Province

The known fauna of the Midway of the western Gulf province includes, roughly, 47 genera of Pelecypoda, 2 of Scaphopoda, 65 of Gastropoda, 1 of Cephalopoda, and 1 genus of Vermes that has been commonly referred to the Gastropoda. For the purpose of determining the relationships of this Paleocene fauna to those which precede and follow, the genera may be segregated into more or less clearly defined assemblages: (1) genera recorded in the Midway that have persisted from the Cretaceous to Recent time; (2) those restricted to the Cretaceous and Paleocene; (3) those restricted to the Cretaceous and early Tertiary; (4) those restricted, at least in the Gulf province, to the Paleocene and early Eocene; (5) those restricted to the Paleocene and Eocene; (6) those restricted to the aleocene, Eocene, and Oligocene; (7) those initiated in the Paleocene and continuing to the Recent.