Geographic Provinces Research Articles

Pennsylvanian Sandstones of the Eastern Interior Coal Basin

ABSTRACT The Pennsylvanian sandstones of the Eastern Interior Coal Basin were studied petrographically and stratigraphically to get a better understanding of source areas, sediment transport patterns, and conditions of sedimentation. The petrographic study was extended to adjoining basins, the Appalachian, Michigan, and northern Mid-Continent, to obtain a regional picture of mineral composition. Stratigraphic patterns are described in terms of general character, lateral persistence, thickness, and contrasts between channel and sheet sandstones. The sheet sandstones are commonly thinner, finer grained, more argillaceous, and more widely persistent than channel sandstones. In the petrographic study, modal mineralogy, quartz variety, and rough size analyses were made of 176 samples and heavy minerals were estimated from 35 samples. The sandstones fall into three petrographic types that correlate with stratigraphic position: orthoquartzites in the basal zone (Caseyville Group), types intermediate between orthoquartzites and subgraywackes in the next higher zone (lower Tradewater Group) and subgraywackes in all higher groups. Although there are minor differences in composition bet een geographic provinces, the major aspect is one of homogeneity over the entire area of the northcentral and northeastern states. Current intensity, the primary factor in sedimentation conditions, varied greatly both locally and regionally, but the range of variability was more or less homogeneous throughout the stratigraphic section and in all of the geographic provinces. Conflicting evidence on marine or nonmarine origin of the sandstones is harmonized, to infer deposition in a combination of a variety of shallow water marine, deltaic, and coastal plain environments. Source areas and patterns of movement of detritus to sedimentary basins were largely inherited from early Pennsylvanian time. After Caseyville time, detritus from the east and northeast moved over the entire basin of deposition, vastly diluting material derived from the north and northwest. Continued mild erosion of source areas throughout Pennsyl anian time led to gradual but incomplete removal of a sedimentary cover and to the exposure of limited areas of igneous and metamorphic rocks.

OUR EXPANDING HORIZONS

Exploration assignments today are more challenging than ever before. The emphasis is on smaller structures and more accurate and deeper interpretations. Many of the more difficult areas, formerly not considered amenable to geophysical exploration, reveal a similarity of problems in widely separated geological and geographical provinces. Geologists and geophysicists are continually broadening their viewpoints because they realize more and more that few areas are unique. Geophysics has made and is continuously making substantial contributions to basic geology. Exploration thinking is broadening steadily toward more definite evaluation of the many types of oil‐bearing traps. Explorationists are learning the principles of sound business risk and thereby expanding their horizons by becoming good businessmen as well as highly trained specialists. The opportunity to expand our horizons further was never more promising than at the present.

Our Expanding Horizons.: ABSTRACT

Exploration assignments to-day are more challenging than ever before. The emphasis is on smaller structures and more accurate and deeper interpretations. Many of the more difficult areas, formerly not considered amenable to geophysical exploration, reveal a similarity of problems in widely separated geological and geographical provinces. Geologists and geophysicists are continually broadening their viewpoints because they realize more and more that few areas are unique. Geophysics has made and is continuously making substantial contributions to basic geology. Exploration thinking is broadening steadily toward more definite evaluation of the many types of oil-bearing traps. Explorationists are learning the principles of sound business risk and thereby expanding their horizons by becoming good businessmen as well as higher training specialists. The opportunity to expand our horizons further was never more promising than at the present. End_of_Article - Last_Page 2779------------

The Land and the Sea: Their Larger Traits

HOMAS Jefferson, while Secretary of State, viewed the North of his time as comprising two great geographic provinces. The one province, facing inland and destined later to be expanded under his own guidance, he denominated the landboard. The outward-facing slope, the Atlantic coastland, was, of course, the seaboard. The former term, which has perhaps never been used since,' serves less to demonstrate Jefferson's originality (which some have lately doubted) than to show that he applied a handy name to a distinctive regional entity, one widely recognized at the time. Others of his contemporaries referred, with less precision and geographic insight, to the back and to its inhabitants as backwoodsmen. On the other hand, the authentic word seaboard has survived in the common language, identifying to all generations the eastern fringe of North America. This elongated if narrow coastal land, possessing no single element of natural unity save frontage upon and contact with a common sea, was without question the most significant part of North at the opening of the nineteenth century. The recognition of this significance did not wait upon the philosophical speculations of a later, possibly more enlightened age. Contemporary observers, distinguished men like Jefferson, others more humble as was the author of the following passage, were keenly aware of the preeminent position of the Atlantic Country. In casting eyes over . . . North America (wrote an author whose name can only be surmised) our observation is powerfully struck by the peculiar situation and appearance of the tract of country reaching from the mouth of the St. Lawrence to the Gulf of Mexico.2 Remarkable attributes of this coastal fringe were its immense frontage on the Atlantic, its innumerable harbors and navigable rivers, and its abundant food resources supplementing those of the land. The whole sea-

Geographic Provinces of Costa Rica

Geographic Provinces of Costa Rica

The Geographic Provinces of Argentina

The Geographic Provinces of Argentina

The Permian in India

The general geographic provinces of India are named, the formations are shown in a table, the permian formations are briefly described, the presence of coal is noted, the widespread glaciation indicated, and the possibility of oil in the Permian discussed.

Geographic Provinces of Angola: An Outline Based on Recent Sources

No part of Africa has been so neglected by writers in English as Angola. This is natural, since the colony always has been Portuguese except for a short period of Dutch rule and since the inhabited sections are separated from British holdings by great stretches of unknown and difficult hunger country. Thus Colonel Statham's venture into this field with Through Angola, a Coming Colony is a novelty. Interested in hunting big game, the greater part of his book covers personal experiences in his pursuit of the antelope; as regards geographic and economic problems it is chiefly useful for what can be read between the lines. Some of the illustrations depict geographical conditions excellently. Two recent expeditions, headed by Count Rohan-Chabot and Professor Taruffi respectively, had scientific objectives-the formner general exploration, the latter a study of agricultural possibilities with a view to Italian immigration. Each expedition confined itself to a single section of the colony and made careful observations. Those of the French mission are objective in tone; the Italian expedition has been written up somewhat in the vein of propaganda for settlers. Marquardsen's monograph on Angola is also based on personal observation in part. But in addition it incorporates all the information available in literature at the time of publication and is an all-round serious geographic study. It bears evidence of the painstaking care and thoroughness with which German scientists generally are accredited and likewise evidence of the complementary undiscriminating acceptance of sources at their face value. In spite of faults, however, this is by all odds the best study of Angola in any language. There is a large-scale map (I: 2,000,000) for relief, drainage, places, transportation, and political subdivisions, in addition to useful sketch maps.

Oil Resources of Peru

Peru has produced petroleum since the early seventies, the first work beingin the Zorritos field, in the Province of Tumbes, adjoining Ecuador. In the early nineties, the Negritos field, in the Department of Piura, cameinto prominence, and by 1905 had attained an annual production of 335,160 bbl.The early development of the field was under the general direction of theLondon &Pacific Petroleum Co., but it is now handled by the InternationalPetroleum Co. In 1900 and 1901, the Lobitos field became the scene of marked activity. In1905, its total production amounted to 75,000 bbl.; it has continued toincrease, as has Negritos. From 1897 to 1902, there was prospecting in the region of La Brieta (orFernandez), on the Mancora River, about 25 to 30 km. from the coast. Smallproduction of a heavy oil was obtained from three different sands. So far asthe author knows, no work has been done in that locality since 1902. There arethus four distinct fields in the north end of the Peruvian coastal plain. The remaining productive locality of Peru is the Pirin or Pusi field, at thenorthwest end of Lake Titicaca, Department of Puno, in southern Peru. The firstprospecting near Pusi was done by Brown Brothers, of Los Angeles, Calif., whoobtained modest production about 1906; according to reports, activities ceasedabout 1914 or 1915. The maximum annual production was obtained about 1908, estimated at 76,000 barrels. Peru possesses two distinct geographic provinces in which we may look forthe development of a larger on industry; namely, the coastal plain province, and the inter-Andean plains. AIME 068–73

Geological Setting of New Mexico

The unique distinction which New Mexico holds in American geology is that it is the meeting-point of four major and diverse geographic provinces. Together these four provinces embraces nine-tenths of the North American continent. Effects of general land depletion under widely different climatic conditions are thus rarely so strongly contrasted. Situated well within the boundaries of the vast southwestern

Some Considerations on the Geographical Provinces of the United States

Some Considerations on the Geographical Provinces of the United States

The Classification of the Pleistocene strata of Britain and the Continent by means of the Mammalia

1. The Principle of Classification . The Pleistocene period was one of very long duration, and embraced changes of great magnitude in the geography of Europe. The climate, which in the preceding Pliocene age, in Northern and Middle Europe, had been temperate, at the beginning of the Pleistocene gradually passed into the extreme arctic severity of the glacial period; and this change caused a corresponding change of the forms of animal life, the Pliocene species (whose constitutions were adjusted to temperate or hot climates) yielded place to those which were better adapted to the new conditions; and since, as we shall presently see, there is reason for the belief that it was not continuous in one direction, but that there were pauses, or even reversions towards the old temperate state, it follows that the two groups of animals would at times overlap, and their remains be intermingled with each other. The frontiers also of each of the geographical provinces must necessarily have varied with the season; and the competition for the same feeding-grounds, between the invading and the retreating forms, must have been long, fluctuating, and severe. The passage, therefore, from the Pliocene to the Pleistocene fauna must have been extremely gradual in each area; and the lines of definition between the two must be, to a great extent arbitrary, instead of being sufficiently strongly marked to constitute a barrier between the Tertiary and Posttertiary groups of life of Lyell, or between the Tertiary and Quaternary of the French geologists. The

On the Distribution of Mastodon in South America

One of the greatest and most significant laws which modern palæontology has unfolded to us, is that principle by which it is definitively ascertained that, as a general rule, the animals of the Post-Pliocene, and indeed all the later Tertiary ages, were restricted to the same great geographical provinces as their representatives in the existing fauna. Amongst the Pliocene Mammalia of South America, we find the same preponderance of the Edentata, the same family of prehensile-tailed Monkeys, and the same typical Llamas and Vicuñas, as we find in the present pampas of La Plata, forests of Brazil, or elevations of the Andes.But we also find animals which, from all our previous pre-conceived associations, we had considered peculiar to the old world. The Elephants, of which one species (E. Africanus) now exists in Africa, a second (E. Indicus) in India, and a third (E. Sumatranus) in Sumatra and Ceylon, apart from the extensive and widely-distributed evidences which we find of their fossil remains in Europe, India, China, and Australia, extended their geographical province in the later Tertiary age over the whole of North America. The species of elephant which we find in Siberia (E. primigenius) has also been found over the whole of the space lately marked on our maps as the United States. South of the 30th degree of N. Iatitude it however gives place to a totally different species of true Elephant (Elephas Texianus, Owen, E. Columbi? Falconer), the molars of which, by their less degree of complexity, were more adapted to triturate the soft succulent herbage of Texas and Mexico. Besides these true Elephants, there existed in North America many individuals of the genus Mastodon, to which the present communication more particularly alludes.