rock has been in part derived from the degradation of the older. Thus, for example, we may find in one part of a country chalk with flints ; and, in another, a distinct formation, consisting of alternations of clay, sand, and pebbles. If some of these... A Manual of Elementary Geology: Or, The Ancient Changes of the Earth and Its ... - Seite 101 von Sir Charles Lyell - 1853 - 512 Seiten Vollansicht -
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