CHAPTER XL 



THE REGION OF THE GREAT MOUNTAIN RANGES. 



Geological Changes on the Earth's Surface. Continents Raised frc m 

 Beneath the Ancient Seas. Basin of the Present Sea. Lands form 

 Elevated Plateaux Around it. Their Average Height. Mean Depth 

 and Area of the Ocean. The Ocean as one Continuous Liquid Expanse. 

 Submarine Mountain Ranges. Islands as Elevated Peaks and Plateaux. 

 The Question of Island Life. American Mountain Ranges. Spurs 

 or Lateral Ranges. The Rocky Mountain System. The Andes System. 

 Probable Results of Upheavals. Fossil Marine Shells Found at 

 Great Altitudes. The Sedimentary Rocks. The Evidences of Up- 

 heaval. Compression or Shrinkage. Distinction between Plutonic 

 and Volcanic Rocks. Contortions of Sedimentary Rocks. Sedimentary 

 Rocks, Raised in Situ, as Plateaux between Mountain Ridges. Par- 

 allel Chains. Their Elevation Probably Simultaneous. Upheaval of 

 the Alps. The Earth's Crust. The Age of Mountains. The Process 

 of Denudation. Ice Wedges. Their Effect in Loosening Rock. Ex- 

 panding Power of Ice. Action of Rains. Landslides. Mountains 

 Originally much Higher than at Present. Slopes of Detritus at Bases 

 of Mountains. The Indian Terai. The Great Plain of Northern India. 

 The Question of its Formation. Tertiary Rocks Underlying the 

 Indian Plain, Flexed Upwards at the Foothills of the Himalayas. 

 Their Fossils all Marine. Crystalline Rocks Form the Higher Peaks. 

 Proofs thus Furnished of the Great Antiquity of the Earth. Whence 

 did the Materials for the Plain Come From ? The Question of its being 

 the Detritus of More Ancient Ranges. Estimate of Bulk of Existirg 

 Asiatic Ranges.' Age of Existing Ranges. Volcanoes. Mountains 

 Generally not Volcanic. A Great Mountain Range the Result of some 

 Gigantic Convulsion of Nature. Probably a Single Operation and not 

 a Series ot Detached Efforts. Vast Antiquity of Mountain Ranges. Rock- 

 cut Gorges. Influences of Mountains on Climate. Line of Perpetual 

 Snow in the Tropics. Causes of Variations of Snow Lines. Himalayan 

 Snows. Snows on the Andes. Peruvian Droughts. The Desert 

 of Atacama. Region of "La Montana." Ranges of Climate on 

 the Slopes of the Andes. Ranges of Plant Life on Mountain 

 Sides. The Pass from Guayaquil to Quito. Magnificent Scenery. 

 The City of Quito. Trails descending into the Tropical Plains. 



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