The Journal of Geology, Volume 2University of Chicago Press, 1894 Vols. for 1893-1923 includes section: "Reviews." |
Overige edities - Alles bekijken
Veelvoorkomende woorden en zinsdelen
alteration Arkansas baselevel basin beds bowlders cañons carbonate Carboniferous character clays Coal Measures coast conglomerate copper Cretaceous crystalline cycad deposits Devonian drift east elevation englacial Eocene epoch erosion eruptive evidence extend fact fauna feet feldspar formation fossils gabbro Geol Geological Survey geologist glacial glaciers gneiss granite gravel Greenland horizon hydrosoma ice-sheet iron Itaituba Lake land later limestone loess lower margin mass material metamorphism Methana miles minerals Miocene moraines mountain occur oil shale origin oxidation Paleozoic plain plants Pleistocene Pliocene portion present probably Professor pyrites quartz quartzite region ridge river rocks sand sandstone schists scicula sediments shales sheet siliceous Silurian slope species specimens strata stratigraphic streams structure sulphide superglacial surface terminal moraine Tertiary theca thecæ thickness tion topography Triassic unconformity upper valley virgula volcanic
Populaire passages
Pagina 455 - Consequently, if the theory be true, it is indisputable that before the lowest Cambrian stratum was deposited long periods elapsed, as long as, or probably far longer than, the whole interval from the Cambrian age to the present day ; and that during these vast periods the world swarmed with living creatures.
Pagina 464 - ... of comprehension. On one occasion the Challenger steamed for two days through a dense cloud formed of a single species, and they are found in all latitudes from the Arctic regions to the equator, in masses which discolor the water for miles. We know, too, that they are not restricted to the surface, and that the* banks of copepods are sometimes a mile thick. When we reflect that thousands would find ample room and food in a pint of water, we can form some faint conception of their universal abundance.
Pagina 464 - ... are never satisfied with slaughter, but kill for mere sport. Insatiable rapacity must end in extermination unless there is some unfailing supply, and as we find no visible supply in the water of the ocean we must seek it with a microscope, which shows us a wonderful fauna made up of innumerable...
Pagina 463 - ... tropical albacore and barracuda. Others, such as the herring, feed upon smaller fishes and the pelagic pteropods and copepods; and others, like the shad, upon the minute organisms of the ocean, but all. with few exceptions, are carnivorous. In the other great groups of marine animals we find some scavengers, some which feed upon micro-organisms, and others which hunt and destroy each other, but there is no group of marine animals which corresponds to the herbivora and rodents and the plant eating...
Pagina 458 - ... echinoderms and brachiopods, that he now has at a marine laboratory; that his studies would have followed the same lines then that they do now, and that most of the record of the past which they make known to him would have been ancient history then. Most of the great types of ancient life show by their embryology that they run back to simple and minute ancestors which lived at the surface of the ocean, and that the common meeting point must be projected back to a still more remote time, before...
Pagina 465 - On the land the mineral elements of plant-food are slowly supplied as the rains dissolve them ; limited space brings crowding and competition for this scanty supply ; growth is arrested for a great part of each year by drought or cold ; the diversity of the earth's surface demands diversity of structure and habit, and the great size and complicated structure of terrestrial plants are adaptations to these conditions of hardship.
Pagina 465 - Modern microscopical research has shown that these simple plants, and the globigerinae and radiolarians which feed upon them, are so abundant and prolific that they meet all demands and supply the food for all the animals of the ocean. This is the fundamental conception of marine biology. The basis of all the life in the modern ocean is found in the micro-organisms of the surface.
Pagina 464 - Herring swarm like locusts, and a herring bank is almost a solid wall. In 1879 three hundred thousand river herring were landed in a single haul of the seine in Albemarle Sound; but the herring are also carnivorous, each one consuming myriads of copepods every day. In spite of this destruction and the ravages of armies of...
Pagina 460 - The everlasting hills are the type of venerable antiquity ; but lingula has seen the continents grow up, and has maintained its integrity unmoved by the convulsions which have given the crust of the earth its present form.
Pagina 466 - Cell-aggregation, the first step towards higher organization, is therefore disadvantageous to the pelagic plants, and as the environment at the surface of the ocean is so monotonous, there is little opportunity for an aggregation of cells to gain any compensating advantage by seizing upon a more favorable habitat. The pelagic plants have retained their primitive simplicity, and the most distinctive peculiarity of the microscopic food-supply of the ocean is the very small number of forms which make...