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abundant acid albite andesite Archean basalt base basin beds biotite building stones Cambrian carbonate Carboniferous cent chemical clays climate coal color composition conglomerate contains Creek Cretaceous crushing strength crystals deposits determined Devonian district drift earth Eocene erosion evidence fauna feet feldspar formation fossils freezing and thawing gabbro Geological Survey geologists glacial glacier grains granite hornblende Huronian hypothesis igneous rocks inch interior Jour Jura Jurassic lakes lavas less limestone lower maps marl mass material matter miles mineral mineralogical momentum moraine Mountains nature nebula observed occur origin orthoclase Pikes Peak plates pore space present probably Professor quarry quartz quartzite region Report represented rhyolite River samples sand sandstone sediments shales Silurian species specific gravity stages strata surface Surv temperature tests texture thickness tion U. S. Geol Upper valley volcanic
Page 416 - All modifications and variations in progressive series tend to appear first in the adolescent or adult stages of growth, and then to be inherited at earlier and earlier stages according to the law of acceleration, until they either become embryonic or are crowded out of the organization, and replaced in the development by characters of later origin.
Page 350 - When reckoned in per cent., the error would be such a small fraction of 1 per cent, as not to be worthy of attention. The specific gravity was determined by dividing the average of the two dry weights by the difference between the average dry weight and the weight of the cube suspended in water.
Page 419 - This statement of Cope might apply equally well to unequal acceleration of characters, but in another part of this same work he gives a clearer statement: " Where characters which appear latest in embryonic history are lost, we have simple retardation, that is, the animal in successive generations fails to grow up to the highest point of completion, falling further and further back, thus presenting an increasingly slower growth in the special direction in question.
Page 175 - Rock Weathering," cites an instance in Montana where he found "along the slopes and valley bottoms numerous fresh, concave, and convex chips of andesitic rock, which were so abundant and widespread as to be accounted for only by the diurnal temperature variations. During the day the rocks became so highly heated as to become uncomfortable to the touch, while at night the temperature fell nearly to the freezing point."1 Livingstone reports the temperature of rock surfaces in Africa to rise as high...
Page 172 - ... remain which is known as the water of imbibition. The sub-capillary pores are conceived to be of such a size, smaller than .00002 centimeter in diameter, as to contain only the water of imbibition. All the water contained in the pores of a rock is known by quarrymen as quarry water. The water of saturation is given off with comparative readiness, while the water of imbibition is retained with great tenacity. And the nearer the pores approach those of sub-capillary size, the greater...
Page 178 - ... water most readily, while the rock faced and hammer dressed stones, on account of their rough exterior, absorb a considerably larger percentage of the water which falls on their surfaces. The exfoliation of sandstone in the large Eastern cities has been mainly attributed to the fact that much of the stone has been laid on edge instead of on the bed. Laying stone on edge in the wall has been practiced at all times, owing to the greater readiness with which it dresses along the bed than across...
Page 711 - They are deeply biconcave, the articular cavities being funnel-shaped and continuous, thus perforating the entire length of the centrum. In a dorsal vertebra the cavities communicate by a very small orifice, while in the posterior the median contraction of the canal is less marked. The posterior cavity is more gradually contracted than the anterior ; in the latter the excavation is, in most of the vertebrae, but slight (except beneath the floor of the neural arch), until it falls rather abruptly...
Page 346 - valuable in determining the ,effect of combining masonry and metal, of joining different kinds of masonry, or of joining new masonry to old ; in calculating the effect of loading a masonry arch ; in proportioning abutments and piers of railroad bridges subject to shock, etc.
Page 178 - ... lowers, the water freezes, and upon the melting of the ice the crack will be found to have widened. Repeat the process and the crack will open still wider. If the process is continued the two walls of the rock will finally be shoved so far apart that the water is no longer retained. The ice acts as a wedge which automatically adjusts itself to the size of the crack, until the opening is sufficiently wide and deep to allow the free passage of the water. Alternate freezing and thawing of the included...
Page 80 - The great comet of 1843 passed within three or four minutes of the surface of the sun, and therefore directly through the midst of the corona. At the time of nearest approach its velocity was 350 miles per second, and it went with nearly this velocity through at least 300,000 miles of corona, coming out without having suffered any visible damage or retardation. To form an idea...