The Elements of economic geology

Bibliographic data

Monograph

Identifikator:: 1773832379

URN:: urn:nbn:de:zbw-retromon-172798

Document type:: Monograph

Author:: Gregory, John W. http://d-nb.info/gnd/11683014X

Title:: The Elements of economic geology

Place of publication:: London

Publisher:: Methuen

Year of publication:: 1928

Scope:: XIV, 312 S.; graph. Darst.

Digitisation:: 2021

Collection:: Economics Books

Usage license:: Get license information via the feedback formular.

Chapter

Document type:: Monograph

Structure type:: Chapter

Title:: Part IV. Engineering geology

Collection:: Economics Books

224 ECONOMIC GEOLOGY on the speed of the river. A go-feet channel at Mildura, on the Murray River, which lost 32} inches of water a day when the stream was flowing, when the water was stagnant lost } inch in the first hour, and after the first day lost only I inch per day. Stagnant water deposits clay on its bed and renders the channel watertight; a flowing stream keeps the clay in suspension and its bed porous. The water that percolates underground forms a widespread sheet in the pores, crevices, and joints in the rocks; the upper surface of this sheet is known as the ** water-table ” (Fig. 57). A pit sunk below the water-table is filled with water and serves as a well; where the ground falls below the water-table in a valley or hill-side, the water outflows as a spring. The water-table is an undulating surface, which “NN Aa at 3 3 Fie. 57.—PosiTioN oF THE WATER-TABLE, The position of the water-table, WT, in an irregular island. SL = sea level. repeats the relief of the ground above though the variations are gentler; it is at the surface on the shore of a lake or the sea ; it rises below hills and falls below valleys. Its varying height depends on surface-tension, by which water adheres to a surface in a thin film, so that it spreads over particles of earth and keeps them wet. Surface-tension and friction prevent the water-table becoming horizontal. As surface- tension is lessened by heat, a rise of temperature sets water free, and thus springs and drains in soils may have an in- creased flow after warm weather. | Tre CIRCULATION OF SUBTERRANEAN WATER—PIEZO- METERS— Lhe passage of water through rocks is subject to the laws that regulate its flow through tubes. Tubes which areless than 5th of an inch in diameter and spaces less than 134th of an inch wide are said to be capillary (or hair-like) and water

Access restriction

Copyright

fullscreen: The Elements of economic geology

Monograph

Chapter

Table of contents

Download

Monograph

Chapter

This page

Image fragment

Citation links

Citation recommendation