. Bulletin of the Geological Society of America. Geology. 362 W. H. TWENHOFEL IMPRESSIONS BY BUBBLES AND RAIN-DROPS or even less (figure 1). After a rain of a few minutes a mud surface becomes thorouglily sculptured through the presence of a multiplicity of coalescing pits (figure 1). Further rain covers the surface with muddy water, previous impressions are destroyed, and there is no possibility of their being made until the water leaves the Figure 3.—i*/(p/e*-s/o«s made ty artificial Hail Eain-drop impressions are also made in sand. If wet sand be struck by rain-drops, impressions
. Bulletin of the Geological Society of America. Geology. 362 W. H. TWENHOFEL IMPRESSIONS BY BUBBLES AND RAIN-DROPS or even less (figure 1). After a rain of a few minutes a mud surface becomes thorouglily sculptured through the presence of a multiplicity of coalescing pits (figure 1). Further rain covers the surface with muddy water, previous impressions are destroyed, and there is no possibility of their being made until the water leaves the Figure 3.—i*/(p/e*-s/o«s made ty artificial Hail Eain-drop impressions are also made in sand. If wet sand be struck by rain-drops, impressions are made and continue to be made until the sand becomes covered w^ith water. These depressions are similar to those made in mud, except that the raised rims are not so sharp or so well de- fined (figure 2). Pits are also made in dry sand and dust by rain-drops, but the margins are less sharp than where the sand or mud is wet. Dry- ing out of the sands tends to make the depressions and the marginal ele- vations less pronounced, and a little wind will altogether obliterate Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Geological Society of America. [New York : The Society]
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectgeology, bookyear1890
