Geology and Man, Page 3 : 無料・フリー素材/写真
Geology and Man, Page 3 / darthjenni
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
|---|---|
| 説明 | 2) 0.8 Mi. A RAIN DROP DIVIDES.It is interesting to note here on this knoll is the north-south drainage divide for the Monument. One would normally expect such a divide to occur on the crest of one of the mountain ranges to the north or south. Actually, water drains from this point either to the northwest via Quail Springs Wash, or to the southeast via Fried Liver Wash into Pinto Basin. The power of running water plays an important part in shaping the desert landscape.3) 1.7 Mi. NATURE'S GUTTER.Here, where run-off water accumulates to from a wash, we can see the effect of water in the desert. During the summer months, intense rainstorms often produce flash flooding along many desert washes. Rocks are physically and chemically broken down by the flowing water. The loosened material is carried to lower elevations by the flowing water and deposited. These deposits, called alluvial fans, will be seen later on the tour.The increased soil moisture along these washes allows certain plants, such as the California juniper and the Parry nolina, to grow here more readily then on the drier surrounding desert.4) 0.3 Mi. OLD EROSIONAL LEVEL.Many of the quartz monzonite boulders to the left (east) of the road bear a distinct groove or band about seven feet above ground level. Geologists believe that this indicated an old erosional level during which the soil surface remained at one point fro some time; perhaps, however, it indicates a more moist prehistoric climate during which time more water was available at ground level and the force of blowing sand eroded the rock more deeply at that point to produce the grooves. Subsequent erosion has lowered the soil to its present level. This illustrates how changes in climate produce corresponding changes in the landscape.5) 0.5 Mi. ROCK PILESThe quartz monzonite, forming the rock piles on both sides of the road, was once part of a molten mass which was forced upward into the overlaying, older Pinto gneiss (pronounced "nice") rock. The monzonite cooled without reaching the surface and crystallized to from solid rock. Erosion over the ages has stripped away the darker Pinto gneiss, exposing the monzonite outcrops as you see them. The mountains to the right (west) are composed primarily of gneiss, and Ryan Mountain, near Cap Rock, displays the contact between the two kinds of rock. Harder, more resistent areas within the monzonite from the numerous rock piles. Many of these have well-defined joint systems, while others have collapsed and are nothing more than jumbled piles of rock.6) 0.6 Mi. ROCK SCULPTUREThe monzonite was fractured into many cracks and joints, usually to sets intersecting at nearly right angles. The agents of erosion are best able to attack the rock along these zones of weakness and weathering occurs at a faster rate. The result is boulders which are roughly rectangular in shape. A massive rectangular boulder to the left of the road illustrates this type of erosion. Many of these boulders weather into grotesque shapes and have been given such descriptive names as the "Skull" (found near Jumbo Rocks) and the "Trojan" and "The Ox" (found along the Hidden Valley Nature Trail). |
| 撮影日 | 2013-07-10 11:53:16 |
| 撮影者 | darthjenni |
| タグ | |
| 撮影地 | California, United States 地図 |
| カメラ | Artisan 730 , SEIKO EPSON CORP. |