On the Need of a Topographical Survey of the Dominion of Canada, And, on a New Nepheline Rock From the Province of Ontario, Canada, And, an Investigation Into the Elastic Constants of Rocks (Classic Reprint)

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Excerpt from On the Need of a Topographical Survey of the Dominion of Canada, And, on a New Nepheline Rock From the Province of Ontario, Canada, And, an Investigation Into the Elastic Constants of RocksA very careful examination, however, of the calcite-bearing occurrences of nepheline syenite in the various parts of this area has clearly shown that in the case of these rocks the cal~ cite represents inclusions of the crystalline limestone penetrated by the intrusion, a fact which receives additional substantiation in the fact that in the Methuen occurrencc. When the wall rock is not limestone, the nepheline syenite does not contain calcite. Along the borders of the intrusion. The nepheline syenite is seen to eat into the limestone and to enclose large masses, the constituent minerals of the syenite growing into the substance of the limestone, often with well defined crystal terminations. These masses often show a coarsening in grain as a resu': of the metamorphic action of the intruding rock. On receding from the contact. The inclusions become less numer ons and smaller, and eventually the large masses are disiate grated into separate individuals of calcite or small groups of calcite 'ns. These. Under the microscope, can be seen as round often perfectly round, inclusions completely enclosed in a single individual of ne heline or other constituent of the nepheline syenite, or lying tween other constituents of the rock, which latter can be seen to have grown into the calcite. In these cases all the minerals are perfectly fresh and unaltered, and, while the constituent minerals of the nepheline s enite rarely show pressure henomcna, the calcite individuals are often seen to be much at and twisted and to display marked strain shadows, the movements displayed being those which overtook the limestone before the intrusion of the syenite into it.About the PublisherForgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.comThis book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully, any imperfections that remain are intentionally left to preserve the state of such historical works.