CONTEXTS. v 



VACE 



rian period. 77. Sir R. Murchison's observations on the changes 

 of the forms of life from period to period. 78. Stratification in 

 undisturbed plains horizontal. 79. Strata thrown into oblique 

 positions by disruption of igneous rocks. 80. Formation of moun- 

 tains. 81. Arrangement of strata on their flanks. 82. Strata 

 sometimes upheaved without being disrupted. 83. Sometimes 

 disrupted. 84. Sedimentary strata deposited subsequently to dis- 

 ruption discordant stratification. 85. How these supply data 

 for determining the epoch of the disruption. 86. Determination 

 of the relative ages of mountains Cumbrians and Grampians 

 much older than the Alps. 87. How inclined strata have enabled 

 geologists to analyse the structure of the terrestrial crust to the 

 level of the igneous rocks. 88. Erosion of stratification by the 

 action of water, and the subsequent deposition of other strata. 

 89. Basalts their character and composition. 90. Various forms 

 of basaltic rocks. 91. Their extensive diffusion over all parts of 

 the earth. 92. Their columnar structure Giant's Causeway. 

 93. Basaltic causeway of the Volant Dykes and colonnade of 

 Chenavari. 94. Veins of basalt. 95. Basalts in mounds. 96. 

 Basaltic grottoes Kase grotto of Bertrich-Baden Fingal's Cave. 

 97. Trachytic rocks. 98. Trachytic mountains. 99. Their 

 origin igneous . . . . . . . . .65 



CHAP. IV. 100. Elie De Beaumont's explanation of the formation 

 of mountain chains. 101. Effects of the earthquake of 1838 in 

 South America. 102. Inference as to the probable effects of 

 the vast earthquakes which produced the great mountain ranges. 

 103. Dislocations in parallel directions produced parallel 

 chains. 104. Origin of mineral veins explained. 105. Veins 

 are found in groups generally parallel. 106. Deposition of 

 rock-salt in cavities of Muschelkalk. 107. Natural agencies 

 still manifested are sufficient to explain all geological phenomena. 

 108. Internal fluidity of the earth. 109. Effects of internal 

 heat on the surface. Why the climates of the higher latitudes 

 at former epochs were similar to those of the tropics at present 

 explanation of the presence of tropical fossils in polar latitudes. 

 110. The undulations and disruptions assumed by geologists 

 as physical causes still proceed, though with less energy. 111. 

 Effects of earthquakes that of Calabria, 1783. 112. Effects 

 in Sicily. 113. Earthquakes at Chili. 114. Earthquake of 

 1819 in India. 115. Like phenomena recorded in all ages and 

 countries. 116. Similar phenomena traditional island of 

 Atlantis. 117. Permanency of the sea-level proves the undula- 

 tions of the land. 118. Undulations of the Swedish peninsula. 

 119. Similar changes in Greenland, and in the Indian archi- 

 pelago. 120. General sinking of South America. 121. Singular 

 example of a submerged forest on the western coast of America. 

 122. Temple of Jupiter Serapis. 123. Historical researches 

 of Professor Forbes. 124. Tradition of a submerged city under 

 Lough Neagh. 125. Why these undulations of the earth's crust 

 might be expected. 126. Effects of disruption of the crust. 

 127. Volcanic eruptions of 1808 in the Azores. 128. The Monte 

 Nuovo . 81 



