Table Of ContentThe Surface of the Earth
ARTHUR BLOOM
L.
FOUNDATIONS OF EARTH SCIENCE SERIES
The Surface of the Earth
T k c 10 . S. co""' i ^
FOUNDATIONS OF EARTH SCIENCE SERIES
A. Lee McAlester, Editor
Structure ofthe Earth, S. P. Clark, Jr., Yale University
Earth Materials, W. G. Ernst, University of California at LosAngeles
The Surface ofthe Earth, A. L. Bloom, Cornell University
Earth Resources, B. J. Skinner, Yale University
Geologic Time, D. L. Eicher, University of Colorado
Ancient Environments, L. F. Laporte, University ofCalifornia at SantaCruz
The History of the Earth's Crust, A. L. McAlester, Yale University
The History ofLife, A. L. McAlester, Yale University
. Oceans, K. K. Turekian, Yale University
Man and the Ocean, B. J. Skinnerand K. K. Turekian, Yale University
Atmospheres, R. M. Goody, Harvard University
andJ. C. G. Walker, Yale University
Weather, L. J. Battan, University of Arizona
The Solar System, /. A. Wood, Smithsonian Astrophysical Observatory
The Surface of the Earth
Arthur L. Bloom
CornellUniversity
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FOUNDATIONS OF EARTH SCIENCE SERIES
A.LeeMcAlester,Editor
Foundations
of Earth Science Series
Elementary Earth Science textbooks have too long reflected
mere traditions in teaching rather than the triumphs and
uncertainties of present-day science. In geology, the time-
honored textbook emphasis on geomorphic processes and
descriptive stratigraphy, a pattern begun by James Dwight
Dana over a century ago, is increasingly anachronistic in an
age of shifting research frontiers and disappearing boundaries
between long-established disciplines. At the same time, the
extraordinary expansions in exploration of the oceans, atmo-
sphere, and interplanetary space within the past decade have
made obsolete the unnatural separation of the "solid Earth"
science of geology from the "fluid Earth" sciences of ocean-
ography, meteorology, and planetary astronomy, and have
emphasized the need for authoritative introductory textbooks
in these vigorous subjects.
Stemming from the conviction that beginning students de-
serve to share in the excitement of modern research, the
Foundations ofEarth Science Series has been planned to pro-
vide brief, readable, up-to-date introductions to all aspects of
modern Earth science. Each volume has been written by an
—— —
authority on the subject covered, thus insuring a first-hand treatment seldom
found in introductory textbooks. Four of the volumes Structure ofthe Earth,
—
Earth Materials, The Surface ofthe Earth, and Earth Resources cover topics
traditionally taught in physical geology courses. Four more volumes Geologic
Time, A—ncientEnvironments, TheHistory oftheEarth's Crust, and TheHistory
ofLife treat historical topics. The remaining volumes Oceans, Man and the
—
Ocean, Atmospheres, Weather, and The Solar System deal with the "fluid
Earth" sciences ofoceanography andatmospheric andplanetary sciences. Each
volume, however, is complete in itselfandcanbe combinedwith othervolumes
in any sequence, thus allowing the teacher great flexibility in course arrange-
ment. In addition, these compact and inexpensive volumes can be usedindivid-
uallyto supplement andenrichotherintroductorytextbooks.
vi
Contents
Introduction 1
Energetics ofthe Earth's surface 5
Gravity: TheLeveler. GravitationalForcesoftheMoonandSun: Tides.
InternalHeat. SolarRadiation. TheHydrologic Cycle.
2
Rock weathering 16
Mechanical Weathering. Chemical Weathering Climatesand Weathering.
Soil. Conclusion.
Rock fragments in motion 40
Mass-Wasting. Slope Developmentand Maintenance.
vii
Streams and channels 53
Dynamics ofFlowing Water. Hydraulic Geometry ofStream Channels.
Transportation andErosion by Streams. The Concept ofthe Graded Stream.
WaterinDryRegions.
5
Life history of landscapes 81
Deductive Geomorphology. Proofs That Landscapes Evolve Sequentially.
InitialLandscapes. Valleys: The Fundamental UnitsofLandscapes.
Old Landscapes and thePeneplain. Theme and Variations.
6
The edges ofthe land 103
EnergyExchangeata Coast. CoastalSediment. CoastalLandscapes.
How To Describe Coasts.
7
Ice on the land 128
Snow, Ice, andGlaciers. Glacier TemperaturesandProcessesofFlow. Glacier
Erosion and Transport. GlacierDeposition. Pleistocene Climatic Change.
Suggestions for further reading 146
Literature cited 147
Index 148
viii
Introduction
The face of the Earth is an honored subject of scientific in-
quiry. Since the earliest days of the shepherd philosophers,
men have meditated on the dubious durability of the "ever-
lasting" hills. Inwhatmaybe theoldest textbook onlandscape
evolution, it is said: "Every valley shall be exalted and every
mountain andhill shallbe madelow; and the crooked shallbe
made straight, and the rough places plain."
How has the surface of the Earth achieved its present
form? Doesitchangeperceptiblywithinthelifetime ofaman,
or within the time of recorded history? What forces shape
landscapes? These questions have been asked by thoughtful
men of every century, and from the time when modern sci-
ences evolved out of the natural philosophy of the Renais-
sance, observation and measurement of the Earth's surface
have been highly regarded scientific activities.
The history of landscape study is an integral part of the
history of geology and geography. In the late eighteenth cen-
tury, Dr. James Hutton ofEdinburgh expounded aprotracted
Theory oftheEarth, with ProofsandIllustrations in which he
argued for the constancy of natural forces through long geo-
