Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ... of land, water, wind, sun, and even life at the time of their deposition are interesting and well worthy of recognition. Casts of sun-cracked surfaces show that a muddy soil had been dried by a,i sun and had been cracked ftHi.'/Kfri 'frfltiWggajteflfBapjia in a similar manner to V//P. '// /'//////////// Plan of cast of a sun-cracked surface. that which we see taking place nowadays; rainprints, by the impressions they have left, show that heavy rains fell upon the soft, yielding mud or sand; side by side with or among these rain-prints may be Fig. 42.--Section through a stone bearing cast of a sun-cracked surface. waves were quietly lapping, even as we see them to-day upon flat reaches of sandy sea-beach; in connection with all of these marked surfaces it is clear that the causes operating to cover up their evidences with a fresh layer of silt or sand must have been both gradual and gentle, or the marks would have been obliterated. How long each stratum of sandstone, shale, or limestone was in process of formation we have no definite gauge wherewith to measure, but some guide has been given us in the remains of upright trees, which were evidently covered up by degrees while still growing, for their roots may be seen attached to the trunk and striking out into the formation around; we know that trees cannot live for long when once partly covered, so that, by comparison with existing similarities, we can arrive at a rough calculation as to the time occupied in forming a certain depth of strata; the guess, however, can be but a vague one, as the conditions under which similar deposits are now forming are very varied and the results far from uniform; but one thing is certain: deposits of fine-grained slates and shales must have been much more gradually laid dow...
Reseña del editor
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ... of land, water, wind, sun, and even life at the time of their deposition are interesting and well worthy of recognition. Casts of sun-cracked surfaces show that a muddy soil had been dried by a,i sun and had been cracked ftHi.'/Kfri 'frfltiWggajteflfBapjia in a similar manner to V//P. '// /'//////////// Plan of cast of a sun-cracked surface. that which we see taking place nowadays; rainprints, by the impressions they have left, show that heavy rains fell upon the soft, yielding mud or sand; side by side with or among these rain-prints may be Fig. 42.--Section through a stone bearing cast of a sun-cracked surface. waves were quietly lapping, even as we see them to-day upon flat reaches of sandy sea-beach; in connection with all of these marked surfaces it is clear that the causes operating to cover up their evidences with a fresh layer of silt or sand must have been both gradual and gentle, or the marks would have been obliterated. How long each stratum of sandstone, shale, or limestone was in process of formation we have no definite gauge wherewith to measure, but some guide has been given us in the remains of upright trees, which were evidently covered up by degrees while still growing, for their roots may be seen attached to the trunk and striking out into the formation around; we know that trees cannot live for long when once partly covered, so that, by comparison with existing similarities, we can arrive at a rough calculation as to the time occupied in forming a certain depth of strata; the guess, however, can be but a vague one, as the conditions under which similar deposits are now forming are very varied and the results far from uniform; but one thing is certain: deposits of fine-grained slates and shales must have been much more gradually laid dow...
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