Stratified Beds Research Articles

The Peacock Range, Arizona

Historical Introduction : Theories of the Basin Ranges VIEWS OF KING AND GILBERT Gilbert9s explanation of the isolated mountain ranges in the Great Basin of the western United States as uplifted and more or less dissected fault-blocks has received, since its first announcement in 1874, several modifications, the most important of which is one proposed two years later by Powell, whose contribution thus made to the solution of the Basin-Range problem is not so well known as it deserves to be. It may be recalled, in this connection, that the first theory to account for the Basin ranges was proposed in 1870 by King, who then announced that they consist of “a series of conformably stratified beds, reaching from the early Azoic up to the late Jurassic period, when these level beds were compressed into vast mountain corrugations and elevated above the sea in a general wide and high plateau,” . . .

Tertiary Stratigraphy and Orogeny of the Northern Punjab

Summary The Tertiary of the Punjab is divided into two principal parts, the marine and estuarine Eocene (Nummulitic) system below, and, unconformably overlying this, a great succession of nonmarine beds representing continental sedimentation from the Oligocene to the late Pliocene or early Quaternary. This nonmarine succession, here named the “Ni-madric System,” includes the Murree and Siwalik series. It comprises over 20,000 feet of fairly well stratified, alternating sandy and silty beds, mainly fine-grained, but coarsely conglomeratic in its uppermost division. It is interpreted as the product of mainly fluviatile, but in part eolian, deposition over fairly flat plains, under a semitropical climate of medium rainfall. The plains extended into the region now occupied by the Himalaya. Evidence of the validity of thickness measurements is afforded by the comparative constancy of individual fine-grained formations, the great thicknesses superimposed in single sections, and by the record here presented of a well 6,000 . . .

On the Clay Pebble-Bed of Ancon (Ecuador)

The clay pebble-bed was first noted by one of us (C. B. B.) in 1919. It was further examined, and part of the outcrop mapped by him in 1922, when its nature and origin were realized. Mr. A. J. Ruthven Murray completed the mapping later. The authors of this paper examined the bed again in 1923, when final conclusions as to its mode of origin were reached. The outcrop is limited in extent, covering not more than 2½ square miles; the numerous small areas are separated by tracts of stratified beds. The best exposure is along the sea-cliffs of Ancon Bay, on the south of the Santa Elena Peninsula. This peninsula is at the northern extremity of the Gulf of Guayaquil, 70 miles west of the town of Guayaquil, and some 130 from the main Andean chain. A typical hand-specimen shows polished rounded or subangular pebbles of harder clay embedded in a matrix of softer clay. The ‘clay-pebbles’ vary from the size of a pin's head up to pieces 2 or 3 inches in diameter, and in rare instances the larger ones themselves contain smaller clay-pebbles. They are easily picked out of the matrix, leaving a smooth polished cast covered by a film of iron-staining. Both pebbles and matrix are grey; the films are grey, green, or brown. In the mass, as in cliff-sections, the clay pebble-bed is seen to contain, in addition, big and partly rounded boulders of sandstone, foraminiferal limestone, and pebbly grit, 2 or 3 feet in

Stages of the Ice Age

Sequence of Glacial and Interglacial Stages Throughout the Glacial period of growth, culmination, and decline of the North American and European ice-sheets, the climate causing the snowfall and ice accumulation fluctuated to such an extent that the boundaries of the continental glaciation were alternately advanced and checked or drawn back. North America had five stages of widely extended icefields. First was the long time of Nebraskan glaciation, followed by a great recession of the ice-borders during an interglacial stage named Aftonian, from its stratified beds and fossils near Afton, in southwestern Iowa. The second and maximum extension of ice accumulation is named, in the Keewatin area of its outflow west of the Mississippi, the Kansan stage, which was broken by the Yarmouth interval of ice melting and retreat. With the Kansan glaciation, but in part spreading across the eastern edge of its drift sheet and melting later from the Mississippi, . . .

The Morrison Formation of Southeastern Colorado

A CONSIDERABLE part of southeastern Colorado and northeastern New Mexico is elevated to a height of about 5000 feet above sea level. The streams of this region have cut canyons to the depth of 700 feet or more. The most notable of these is the canyon of the Cimarron in New Mexico, and that of the Purgatory, or Las Animas, in Colorado. The studies of which the conclusions are given in this paper, were carried on mainly in the canyon of the Purgatory and its tributaries, although a side trip was made to the canyon of the Cimarron. The region examined is shown in the accompanying sketch map (Fig. I). The canyon walls are steep and bare and complete sections are easily obtainable. The lower half is red sandstone overlain with gypsum (the Red Beds); the surface rock is also sandstone (Dakota.) Between this upper sandstone and the gypsum is the shale formation of which I specially write. The shales are found throughout the region examined wherever the streams have cut through the upper sandstone. Two detailed sections were taken at the points indicated on the map by a cross (X), section I, at the junction of Plum and Chaquaqua canyons, and section 2, in Red Rocks Canyon. Since the canyons do not cut entirely through the Red Beds at any point within the area examined, it is impossible to accurately estimate their full thickness; the sections, therefore, represent only the upper part of these beds. For some distance above the bottom of Plum Canyon (section I) the rock is evenly stratified, ripple-marked and somewhat shaly. A limestone layer four feet thick near the bottom extends uninterruptedly for many miles and forms a convenient line of reference. Above these evenly stratified beds occurs a series of massive layers of coarse red sandstone aggregating about 250 feet in thickness. This series forms the steepest and

The Igneous Rocks and Associated Sedimentary Beds of the Tortworth Inlier

I. Introduction The Silurian rocks of the Tortworth district in Southern Gloucestershire present several features of geological interest. Lying to the north of the horseshoe ridge of Carboniferous Limestone, which forms the rim of the Bristol Coalfield, they share in the synclinal disposition of the Palæozoic strata. They underlie the attenuated Old Red Sandstone, which in this district is not more than some 200 or 300 feet thick; but the exact relation of Silurian to Old Red is nowhere clearly seen. The strata include beds of Ludlow, of Wenlock, and of Upper Llandovery age, the last-named being originally regarded as Caradoc. The chief points of interest are: (1) the remarkable attenuation of the upper strata, the Ludlow Beds not exceeding 100 feet in thickness, and the Wenlock attaining a thickness of at most 700 feet, probably less; (2) the limited number of fossils recorded; and (3) the occurrence of igneous rocks interbedded with the Upper Llandovery strata, and passing up to, or perhaps just into, the Lower Wenlock Beds. It is with these igneous rocks and their relation to the sedimentary beds that this paper deals. The trap-rocks were carefully studied and described by Thomas Weaver in 1819. He regarded it as ‘evident that the trap constitutes discontinuous beds included in and parallel to the continuous series of the stratified transition-beds’; but, as a faithful disciple of Werner, he hastened to add that, since these stratified beds were ‘undeniably aqueous products, I do not perceive how we can avoid extending

Marine and freshwater beaches of Ontario

Research Article| January 01, 1901 Marine and freshwater beaches of Ontario A. P. COLEMAN A. P. COLEMAN Search for other works by this author on: GSW Google Scholar Author and Article Information A. P. COLEMAN Publisher: Geological Society of America First Online: 02 Mar 2017 Online Issn: 1943-2674 Print Issn: 0016-7606 © 1901 Geological Society of America GSA Bulletin (1901) 12 (1): 129–146. https://doi.org/10.1130/GSAB-12-129 Article history First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A. P. COLEMAN; Marine and freshwater beaches of Ontario. GSA Bulletin 1901;; 12 (1): 129–146. doi: https://doi.org/10.1130/GSAB-12-129 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Marine DepositsThe Pleistocene marine beds of Ontario have been studied for many years and have yielded a great number of fossils at different points along the Saint Lawrence and Ottawa and in the country between these two rivers, as well as along the rivers flowing north into Hudson bay,* proving that the sea once occupied these regions for a length of time sufficient to form beds of clay and sand often more than 100 feet thick. Sir William Dawson has divided these deposits into “Leda clay” and “Saxicava sand,” the names being derived from the commonest fossils occurring in them. The Leda clay usually rests on boulder-clay, and the Saxicava sand usually overlies the Leda clay, so that in general one may say that the stratified marine beds were formed later than the last retreat of the ice from the region mentioned.Probably the beds most productive in fossils . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

On the Calton Hill and its relation to the rocks in the neighbourhood

My original intention was merely to bring before the notice of the Society a small section recently exposed in making a drain at the Low Calton, where the lowest portion of the traps of the Calton Hill was exposed, but seeing that a good deal of interest is centred on the hill at present owing to the making of the tunnel and other alterations going on in connection with the North British Railway, I have taken the liberty of calling attention to a few facts and theories connected with the hill. The Calton Hill has not received so much attention from geologists as its larger neighbour, Arthur's Seat. This is no doubt due to the fact that its structure is much simpler than that complicated and puzzling series of rocks included in the Queen's Park. Still a number of well-known geologists have described its structure, and others have noted the minerals connected with it. Cunningham, in his “ Geology of Midlothian,” describes the rocks of the Calton Hill as a series of traptuffs and porphyries dipping to the east, and he seems to have considered them all intrusive. He also mentions certain sandstone strata dipping under the traps of the hill that were exposed in excavations made for the foundations of the Waterloo Bridge. He likewise calls attention to the stratified beds that overlie the strap at the eastern end of the hill. Maclaren, in his “ Geology of Fife and the Lothians,” gives a description along with a diagram

The Geology of Monte Chaberton

I n the study of the geology of the Cottian Alps the problem that has given rise to most difference of opinion is the age of the beds of serpentine and ‘pietre verdi’ which occur so abundantly among the schists of this district. Most geologists now admit them to be altered igneous rocks, though the theory of their being bedded sediments still lingers in Italy. As to their age, however, there is much greater uncertainty, so that in spite of all the work that had been done in the Cottians, when the subject was considered in 1890 in the description of the Variolitic Rocks of Mont Genèvre, it was only possible to conclude that “we must in fairness merely style them Post-Carboniferous until further evidence is forthcoming.” The locality that offered the best prospect of the solution of this question seemed to be on the flanks of Monte Chaberton, the great dolomite mass on the north side of the well-known pass of Mont Genévre. Here a typical series of the intrusive rocks is associated with stratified beds containing three distinct sets of fossils, namely, those of the radiolarian phthanites of Cesana, the Gyroporella and other Triassic organisms of Clavières, and those hitherto known only from some fallen boulders on the eastern talus-slopes of Chaberton. The age of the first and last of these was uncertain, and it was necessary to determine that of the last before any great advance could be made. The fossils in the boulders had been found on

On some Erratics in the Boulder-clay of Cheshire, &c., and the Conditions of Climate they denote

The glacial phenomena in the valley of the Mersey indicate that, though during that period the country was entirely covered with ice and snow, these accumulations were no greater than were derived from the snowfall on the water-slopes of this and its tributary valleys. The glacier-striæ on the surface of the Triassic rocks coincide in direction with those of the respective valleys, or they have a direct reference to the contour of the ground. Taking “Happy Valley” (now Borough Road), Birkenhead, as a typical example, the bottoms of the valleys, where channels have been in pre-Glacial times, are filled to a limited height with irregularly stratified beds of sand and gravel, their presence in other valleys being revealed by excavations and borings for wells, &c. The sands have been derived from disintegration of the Trias; whilst the pebbles are similar to the erratics so abundant in the Boulder-clay, excepting that all traces of striæ &c. have been removed, it is presumed, by water which, holding sand in suspension, issued from beneath glaciers. On these gravels &c. is situated Boulder-clay containing a much larger proportion of sand and pebbles than the Boulder-clay proper. The flanks of the valleys frequently have rock-surfaces covered with unstratified sands and angular fragments of sandstone, without intermixture of erratic pebbles; they are considered to be moraine accumulations left by glaciers which extended into the sea. The whole is covered with Boulder-clay, a reddish-brown unstratified clay containing pebbles and boulders irregularly dispersed through it. Besides the accumulations

Notes from a diary in 1862 of some geological observations made (1) at points along the line of Caledonian Railway from Carstairs southwards, (2) at Moffat and (3) at Loch Skene

(1.) Caledonian Railway. 1. In the Carstairs, district enormous accumulations of sand occur, forming beds stratified in layers nearly horizontal. Some of the sections exposed are from 60 to 70 feet deep. In several of these, many pebbles, including lumps of coal, the largest about the size of a man’s head. These so rounded as to indicate that they have undergone much friction in transitu. These sand deposits seem to rest on boulder-clay, a small patch of which is seen in a stream at one place adjoining. The district, covered by these deposits, comprises several square miles, and is on a pretty uniform level of about 700 feet above the sea. They occasionally form mounds and elongated ridges, which may be due either to original formation or to subsequent denudation. If originally deposited in the sea the sediment composing them would be laid down as submarine banks; or by the action of currents, they may have acquired the forms they now exhibit. To the north of Carstairs village there are some long ridges of gravel, tolerably free from sand, and consisting of well-rounded pebbles and occasional boulders. The pebbles do not form regularly stratified beds. Though most of those gravelly deposits run in a direction east and west, some follow a sinuous line and even unite with others, so as to contain small lakes or pools of water. The ridge enclosing one of these lakelets had been cut through to drain it, and thus a good opportunity was afforded of

On some sections of boulder clay, peat, and stratified beds recently exposed at Redhal, Slateford, near Edinburgh

The new quarry in which these sections are exposed lies to the north of the quarry, hitherto called Redhall Quarry, and is separated from it by the canal and the Caledonian Railway. Both quarries are in the same line of strike in the carboniferous rocks, which dip to the west along this line. Unfortunately, a large portion of the beds overlying the sandstone had been removed before I saw the sections, and the process of sloping the banks had been going on for some time—a very unlucky proceeding for the geologist. Still, there was enough left to show the very interesting and instructive sections we have in this locality. At the south end of the quarry, where the process of tirring was going on when I first observed it, the sandstone beds, as I have remarked, dip to the west. At the east side of the section the beds are sharp, unweathered, and truncated, the spaces between the ends of the beds being firmly packed with hard, dry boulder clay, full of both angular and rubbed stones. The two lowest beds of sandstone exposed are each four or five feet thick. The ends of these beds are also truncated, showing as it were a cliff from eight to ten feet deep, facing the east. This is also filled up with boulder clay, enclosing large angular blocks of sandstone, evidently derived from the end of the beds, and also a large number of smaller stones, scarcely any of them rubbed or

On the Section in Cowden Glen, Neilston, Renfrewshire, with Remarks on the Upper Boulder Clay

In making the above railway throughout Cowden Glen, the excavations laid open a series of beds, consisting of stratified clayey mud, sand, gravel, and peat. These beds, evidently of lacustrine origin, commence about three-fourths of a mile south-west from Crofthead, or Neilston Station, and continue in the cutting for nearly half a mile as it proceeds towards Shelford. On the east end of the stratified beds, the glen is less than 100 feet wide; the north side forming a bold escarpment nearly 80 feet high. The south side has less height, falling back in undulating knolls, and forming a rugged but not unpicturesque landscape. But as it extends towards Shelford, the hills on each side lose their escarpment character, falling back with more regular declivity, and giving the glen more the character of a valley, until, at Shelford, the breadth of the clay deposits, forming the bottom of the valley, is nearly half a mile broad. The glen, or valley, has been caused by a large break in a ridge of trap, which divides the carboniferous strata of the Levern valley from that of the Lugton, lying to the south-west of Shelford. The break in itself is of geological interest. The trap on its north side is that soft peculiar porphyrite of the Gleniffer range of hills, while on the south side it is porphyritic claystone, intercalated with layers of greenstone, and is certainly a subsequent deposit to the porphyrite of the north side. At the point where the glen This 250-word extract was created in the absence of an abstract

III.—On the Organic Remains found in Clay near Crofthead, Renfrewshire

The number of the Geological, Magazine, for September last, contained a description, by Mr. James Geikie, of stratified beds of sand and mud intercalated with Boulder-clay, which occur in the Cowdon valley, near Crofthead. His reference to some contained vegetable débris induced me to make an examination of the strata, which has resulted in revealing an abundance of organic remains quite exceptional in such deposits.

2. On the Occurrence of Stratified Beds in the Boulder Clay of Scotland, and on the Light which they throw upon the History of that Deposit

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The Common Fossils of the British Rocks

The unstratified Plutonic rocks are considered to form, as we have intimated, the common base of the stratified beds all over the globe. With them, however, we have little to do in this place. Our labours commence with the stratified, and we should even have excluded the so-called “Azoic,” had not that term been recently subjected to considerable restriction by the discovery of organic remains in some of its members; and, as it is still likely, by further researches, to be totally absorbed into the Palæozoic system, we append an ideal section representing the sequence of formation of the most ancient groups of fossiliferous rocks, with the relative position of those primordial conglomerates, flags, and schists in which as yet no organic remains have been found. Whether, at the vastly remote period at which those isolated masses, still ranked as Azoic, were formed, the advent of life had really not taken place on our planet, or whether those masses are the few remnants of a still older stage of our world than any presented to us by the recognised series of fossiliferous rocks, has yet to be determined by the investigations of geologists—but in their massiveness and their vast age they must ever be regarded with veneration and wonder.

On the Silurian Rocks of the South of Scotland, and on the Gold Districts of Wanlockhead and the Lead Hills

Mr. Harkness considers that the mineral axis of the system of Silurian rocks in the south of Scotland is the syenitic mass of Criffel. The rocks lying next to the syenite are in a highly metamorphic state, but wherever bedding can be traced, it is found that the strata on the south side dip to the south, and on the north side to the north; which last northerly dip (or to speak more correctly N.N.W. dip) continues with little exception to the northern margin of the Silurian rocks. The lowest regularly stratified beds which can be observed on the north of Criffel are near Woodside Hill, in the parish of New Abbey, Kirkcudbrightshire, where the dip is N.E., but at no great distance to the west of this the usual N.N.W. dip obtains. By following these beds northward from Lochaber (where the syenite again occurs), an ascending section is procured for six miles, the dip exceeding 70°. The rocks consist of thick and thin greywacke sandstone (in contact with the igneous rock), frequently showing the laminæ of deposition, succeeded by thin-bedded flaggy greywacke, resembling flinty slate. Then follow in succession (at Longwood) greenish-grey, curved, laminated beds, intersected by calcspar veins,—a series of chloritic shales, interstratified with thin beds of fine-grained greywacke sandstone,— shales,—and lastly sandstone and flaggy beds, which form the hills up to the Nick of Bennerick.

On the Occurrence of Marine Shells in the Stratified Beds below the Till

I n the basin of the Clyde, the Till or unstratified boulder clay generally rests upon the beds of the coal formation, or upon rocks of an earlier date; and these subjacent rocks are almost always fractured where they are in contact with the Till. There are however exceptions; sometimes the Till rests upon scratched but unbroken surfaces of those rocks; and sometimes, but very rarely, we find immediately below the Till beds of sand, gravel, and laminated clay,—fragments apparently of an older alluvial covering, which has not been entirely removed by the cause, whatever it was, which lodged the Till on the surface. Until the discovery which I am about to communicate, no marine remains had been found in the beds underlying the Till. We had therefore no direct evidence to prove that those beds are of the same age as the deposits which lie above them. Having been informed by Mr. John Craig, F.G.S., that a bed of shells had been discovered near Airdrie, much higher than any previously found in Scotland, I considered it of importance to ascertain the exact amount of the elevation above the present level of the sea, as well as the species of the shells, and the nature of the deposit in which they were found. Mr. Craig kindly accompanied me to the locality, which is near the Monkland Iron Works, and about fourteen miles to the south-east of Glasgow. The shelly deposit in question proved to be a bed of the Tellina proxima

On the Origin of Slaty Cleavage

Before describing the theory I have propounded to account for what is called “slaty cleavage,” it will probably be the best for me to explain briefly the nature of this structure and of the problem to be solved. Most stratified rocks can be split with more or less facility in the plane of their bedding, but in certain districts, greatly disturbed by elevatory forces, besides this line of weakness, there occurs another, only remotely connected with the bedding, and often so much more decided, that they were at first confounded, and the stratification overlooked, until the true nature of cleavage was pointed out by Professor Sedgwick. In most districts possessing cleavage, the stratified beds are much contorted, and dip at all angles, whilst the cleavage passes through them with more or less regularity, in some cases quite independent of the bedding. I should occupy far too much time if I were to describe one-half of the facts connected with this very extensive subject, and shall therefore confine myself to hut few. It is most important to bear in mind that cleavage is quite distinct from jointed structure. Joints are mere cracks and fractures, whereas cleavage is a structural weakness affecting the whole mass of rock. The question, therefore, is, how this structural weakness was developed? Mr. Fox, of Cornwall, found that a kind of laminated structure was produced by passing an electric current through clay, and Hunt has since repeated, confirmed, and extended his observations. I, however, think this electrical ...