Unnamed Unit Research Articles

Paleozoic Stratigraphy of Great Basin: ABSTRACT

The present Great Basin embraces deposits of an inner (eastern) geosyncline and an outer (western) geosyncline. Disregarding the problem of naming and classifying these two features, attention will be focused on the better known eastern trough where an intensive search for oil is currently in progress. Outstanding features of the sedimentary section are: (1) preponderance of marine chemical rocks, (2) great thickness of certain units, and (3) evidences for mid-Paleozoic orogeny. Base of the sedimentary section almost everywhere is a thick quartzite (Prospect Mountain-Brigham) which transgresses through time from late pre-Cambrian to late Cambrian. Above this is an accumulation of Cambrian carbonate rocks reaching a thickness of 10,000 feet in the central part of the trough. The Cambrian passes into Ordovician with little evidence of hiatus, and carbonate sediments (Pogonip-Garden City) continued to accumulate giving a complete record of the period up to about Chazy time. A useful key bed and one of the few clastic units, the Eureka-Swan Peak, was then laid down. Late in the Ordovician a second, thinner dolomite unit (Fish Haven-Hansen Creek) came into being. The Silurian system is represented by a rather uniform, scantily fossiliferous dolomite formation (Laketown-Lone Mountain-Roberts Mountain) which accumulated during the Niagaran epoch. Thickness averages between 500 and 1,000 feet. All epochs of Devonian time are represented, but Middle Devonian rocks are the most extensive. Key locality for the system is the Roberts Mountains region of Nevada where about 4,500 feet of Devonian rocks are present. Dolomite appears to be the dominant rock of the thinner sections. Much in the way of correlation of Devonian units in western Utah remains to be done. The Mississippian is lithologically the most varied of the Paleozoic systems. Sediments reflect orogeny in west-central Nevada and range from conglomerates and redbeds on the west through quartzites, sandstones and black shales to limestones on the east. Maximum thicknesses are on the order of 5,000 feet. Numerous named and unnamed units remain to be more thoroughly studied. Continuous sedimentation from Mississippian into Pennsylvanian is indicated. The most characteristic and striking Pennsylvanian unit is the fusulinid-bearing Oquirrh formation which shows crude cyclic deposition, involving a variety of chemical and clastic rocks. This unit may reach a thickness of 20,000 feet in the east-central Great Basin, but there is a decrease in thickness and loss of certain intervals westward. Again sedimentation disregarded systemic lines and Permian Wolfcamp fusulinids are found in the upper part of the Oquirrh. Following the Oquirrh is a variety of thinner Permian units such as the Phosphoria, Supai, Kaibab, and unnamed formations in Nevada. Redbeds, gypsum, phosphate rock and massive chert are rather unusual constituents of this interval. End_of_Article - Last_Page 1107------------

Devonian System in Central and Northwestern Montana

The Devonian strata of central and northwestern Montana are confined to an Upper Devonian age. In central Montana these rocks are divided, in order of increasing age, into the Three Forks formation, predominantly shale; the Jefferson formation, composed of an upper dolomite member, including some anhydrite or evaporite-solution breccia, and a lower dense limestone member; and an unnamed basal unit of shale and shaly dolomite which bears a transgressive relationship to the underlying Ordovician and Cambrian. In northwestern Montana these terms are not applicable and the Devonian is divided, in descending order, into arbitrary units A, B, and C. Unit A is dolomite and anhydrite, or evaporite-solution breccia, unit B is dense limestone, and unit C is a red shale and shaly do omite sequence resting on the channeled surface of the Upper Cambrian. Oil is produced from the Devonian of south-central Alberta and gas has been encountered in it in Montana. Petroleum possibilities appear to be confined to the dolomites of the Jefferson formation and unit A, and it is suggested that these possibilities may have been enhanced by favorable depositional environments and post-depositional effects.

Late Paleozoic and Early Mesozoic Stratigraphy of Uinta Mountains, Utah

At the western end of the Uinta Mountains, Triassic rocks rest unconformably on the Permian Park City formation. From the base upward the Triassic rocks are (1) red Woodside shale, (2) marine Thaynes limestone, (3) Ankareh redbeds and (4) a conglomerate and overlying sandstones and shales. The Thaynes thins and tongues out eastward, and east of its edge the Woodside and the Ankareh can not be differentiated. The conglomerate, sandstones, and shales were classed as basal Nugget sandstone, Jurassic, by Boutwell (1912), but were excluded from the Nugget (Navajo sandstone) by Heaton (1939), leaving them without a name. At the eastern end of the mountains, Woodside redbeds rest on the Pennsylvanian Weber sandstone. The lower part of the Woodside is the time equivalent of the upper Park City (Phosphoria). The Woodside is cut by an unconformity above which lies a conglomerate. The conglomerate was questionably classed as the basal member of the Ankareh by Sears (1926). The upper part of the Ankareh (?) of Sears consists of varicolored shales and sandstones and is directly overlain by the massive Navajo sandstone. The conglomerate and the overlying varicolored beds are readily recognized from one end of the range to the other and constitute an unnamed lithologic unit which lies unconformably above the type Ankareh and below the restricted Nugget at the western end of the mountains, and unconformably above the Woodside and below the Navajo at the eastern end of the range. This unit is here named the Stanaker formation and the basal conglomerate, or grit, is named the Gartra grit member of the Stanaker formation. They are probably Upper Triassic in age. The Jurassic formations of the western Uinta Mountains, from base upward are (1) Nugget sandstone, (2) Twin Creek limestone, (3) Preuss redbeds, (4) Stump sandstone, and (5) Morrison formation. Eastward along the mountains (1) the Nugget sandstone persists but is called Navajo on the east, (2) the Twin Creek limestone intertongues with the Carmel redbeds, (3) the Preuss redbeds grade into the cross-bedded Entrada sandstone, (4) the Stump sandstone grades into Curtis shales and limestones, and (5) the Morrison thins and becomes less conglomeratic. At the eastern end of the Uinta Mountains the Carmel redbeds thin out so that the Navajo is directly overlain by the Entrada, forming a single cross-bedded sandstone unit.

Correlation of the Permian of Southern Utah, Northern Arizona, Northwestern New Mexico, and Southwestern Colorado

The Permian of southern Utah, northern Arizona, northwestern New Mexico, and southwestern Colorado is conceived as bounded below, except in the Grand Canyon, by conformable Pennsylvanian limestone (Callville limestone in the extreme west, an unnamed unit in north-central Arizona, Hermosa formation in San Juan Valley and southwestern Colorado, Magdalena limestone in northwestern New Mexico), and above by unconformable Triassic deposits (Moenkopi formation, Shinarump conglomerate, and Dolores formation, in order from west to east). In the Grand Canyon the underlying beds are Mississippian (Redwall) limestone. Three main types of Permian sequence occur: that of the Grand Canyon, with the Supai formation and Hermit shale (red beds), Coconino sandstone (light-colored, cross-be ded), and Kaibab limestone, named in ascending order; that of Monument Valley and adjacent country north and south, with the Rico formation (red beds and limestone) below and five units above, here treated as parts of the Cutler formation and named in ascending order the Halgaito tongue (red beds), Cedar Mesa sandstone member (light-colored, cross-bedded), Organ Rock tongue (red beds), De Chelly sandstone member (light-colored, cross-bedded), and Hoskinini tongue (red beds); that of southwestern Colorado, with the Rico formation (red beds and limestone) below and the undivided Cutler formation (red beds) above. The relations of these units to one another are shown in a number of cross sections and the earlier nomenclatures are correlated with that used here. Apparently the Permian began ith the widespread deposition of red beds derived from the east, except in the extreme west part of the area where light-colored sands were laid down. In the east a few marine limestones (Rico) interrupted the sequence of red materials, representing incursions of a sea from the east. These first red deposits were followed by light-colored sands coming from the northwest (Cononino, et cetera), which interfingered End_Page 1413------------------------------ with the red materials that still continued to come in from the east. Then marine waters gradually advanced from the west across the western half of the area, depositing chiefly limestone (Kaibab). East of the sea the light-colored sandstones were the chief deposits in a wide zone, and still farther east the red materials prevailed. Finally, the sea withdrew with seeming abruptness and the whole area was exposed to the period of erosion represented by the unconformity at the base of the Triassic.

Name for the Positive Nucleus

A NAME is wanted for the fundamental unit of matter, which is also the unit of positive electricity as at present known. The name “electron” is best limited to the unit of negative electricity, about which a good deal is by this time known. Less is known about the positive unit, but it appears to be the brick of which all atoms are built up, electrons acting as cement. Nearly all the mass belongs to the positive unit, and the simplest atom—namely, hydrogen—appears to consist of one positive and one negative unit electric charge. The heaviest atom known has ninety-two such charges, and among the chemical elements are all intermediate grades. Prout's famous hypothesis that every element was a multiple of hydrogen is thus, with some modification, being confirmed, though the unnamed unit is not exactly an atom of hydrogen, but the nucleus, the main substance, of that atom.