Natural Environmental Change: The Last 3 Million Years

By A. M. Mannion | Go to book overview

3

The record of environmental change in ocean sediments

3.1

Introduction

One of the most significant advances in the elucidation of the natural environmental change of the last 3×106 years was the inception of research on ocean-sediment cores in the 1950s (Section 1.2.2). Since then, a wealth of information has been obtained from a large range of cores obtained from such diverse locations as the Antarctic Ocean and the Caribbean. Moreover, in the last 40 years a range of techniques has been devised to extract the physical, chemical and biological secrets concealed within the oceans’ sediments.

The major contribution of ocean-sediment studies to environmental-change research lies in their capacity to provide an unbroken record for the last 3×106 years. This contrasts with the fragmented nature of the terrestrial record of environmental change. The availability of long sequences of palaeoenvironmental information from various parts of the world is now expediting the establishment of a global framework for environmental change. In particular, the use of ratios of isotopes of oxygen and their dated changes through time have allowed the identification of chronostratigraphic units, i.e. firmly dated units, which are referred to as oxygen isotope stages or marine isotope stages. In order to establish regional and global relationships between disparate deposits, these deposits are increasingly being referred to, and correlated with, marine isotope stages. As well as this framework function, data from ocean-sediment cores have been used to reconstruct sea-surface temperatures, the degree of aridity/humidity on the continents, changes in global ice volume and glacial/interglacial reorganisation of the global carbon cycle.


3.2

Theory and methodology

The oceans currently receive between 6×109 and 11×109 tonnes of sediment annually. Whilst the volume would have varied in the past, the volume of sediment entering the ocean basins would have been considerable as the continents were

-33-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Note: primary sources have slightly different requirements for citation. Please see these guidelines for more information.

Cited page

Bookmark this page
Natural Environmental Change: The Last 3 Million Years
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen
Items saved from this book
  • Bookmarks
  • Highlights & Notes
  • Citations
/ 198

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA 8, MLA 7, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Search by... Author
    Show... All Results Primary Sources Peer-reviewed

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.