Origins of Mountains - Mountain Geography: Physical and Human Dimensions - page 18

CHAPTER TWO
Origins of Mountains
JOHN F. SHRODER JR. and LARRY W. PRICE
Views about mountain origins have changed considerably through time. During the
Middle Ages and early modern Western Europe, mountains were regarded as “monstrous
excrescences of nature”; a prevailing view was that they had been created as punishment
after man's expulsion from the Garden of Eden. This idea apparently had its origin in
the fact that the story of creation in Genesis makes no mention of mountains. Explana-
tions of mountain creation differed: Some said that interior fluids ruptured the spherical
surface and piled up in great heaps; others leaned toward the cataclysmic biblical flood.
Although more advanced ideas had been developed by the ancient Greeks and medieval
Arabs, such was the power of theology in Western Europe that science retrogressed. It
was not until the bond between religion and science was severed in the 17th and 18th
centuries that major scientific advances were made. Once begun, science progressed
rapidly, and a number of plausible theories postulated the origin of mountains. Current
attempts by enthusiasts of the oxymoronic “creation science” to set back the scientif-
ic clocks notwithstanding, advances have steadily increased understanding of the evolu-
tion of the Earth and its mountains (Turcotte and Schubert 2002; Owens and Slaymaker
2004; Owen 2004; Oilier 2004; Williams 2004). Earth's crust is known to be divided into
moving rigid plates; where plates pull apart, new crustal material is produced at spread-
ing center rifts, and where plates collide they descend back into the mantle in submarine
trenches and subduction zones, or buckle upward into mountains.
Characteristics of Major Mountain Ranges
The most important clues to the origin of mountains are the distribution of mountain
ranges over the globe and their structure and material composition. Both point to a fun-
damental association between oceans and mountains. Mountain ranges tend to run in
long, linear belts along the margins of continents such as the Andes in South America,
as well as in continental interiors such as the Urals or the Himalayas (Fig. 2.1). One long
belt extends along the periphery of the Pacific Ocean, and another runs east-west along
the “underbelly” of Eurasia. The distribution of mountains closely follows the distribution
of earthquakes, fault zones, volcanic activity, ocean trenches, and certain curved chains
of islands (island arcs).
Many coastal zones, as well as being less stable than most continental interiors, are
made of much younger rock. Most continental interiors are composed of ancient crys-
talline cores of Precambrian granitic and metamorphic rock surrounded by patches of