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- 2009-7-26
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发表于 2007-3-21 19:47
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The Rock Cycle岩石循环
Rocks are constantly being formed, worn down and then formed again. This is known as the rock cycle. It is like the water cycle but it takes a lot longer. It takes thousands and millions of years for rocks to change. Types of Rocks :
Rocks are divided into 3 types:
Igneous 火成岩
Sedimentary 沉积岩
Metamorphic 变质岩
Igneous Rocks
Igneous means made from fire or heat. When volcanoes erupt and the liquid rock comes up to the earth's surface, then new igneous rock is made. When the rock is liquid & inside the earth, it is called magma. When the magma gets hard inside the crust, it turns into granite. Most mountains are made of granite. It cools very slowly and is very hard. 火成岩因受热形成。当火山爆发,岩浆喷出到地表时而形成。岩浆在地壳中冷却变硬,成为花岗岩。大多数山都是由花岗岩构成。花岗岩冷却非常慢,硬度很高。
When the magma gets up to the surface and flows out, like what happens when a volcano erupts, then the liquid is called lava. Lava flows down the sides of the volcano. When it cools & turns hard it is called obsidian, lava rock or pumice - depending on what it looks like. 火山爆发时,地表的岩浆被称作火山熔岩。火山熔岩延火山流下,根据外形不同冷却后成为黑曜石、熔岩石或浮石。
Igneous rocks form when molten lava (magma) cools and turn to solid rock. The magma comes from the Earth’s core which is molten rock . The core makes up about 30% of the Total Earth Mass (31.5%)火成岩由岩浆冷却变硬后形成。岩浆来源于融化的地核。地核占地球总重量的30%。
There are 5 kinds of igneous rocks, depending on the mix of minerals in the rocks. 根据岩石中所含矿物质不同,火成岩分为五个不同种类:
Granite contains quartz, feldspar & mica花岗岩含石英、长石和云母
Diorite contains feldspar & one or more dark mineral(暗色矿物). Feldspar is dominant. 闪长岩
Gabbro contains feldspar & one or more dark mineral. The dark minerals are dominant. 辉长岩
Periodotite contains iron and is black or dark.
Pegmatite is a coarse-grained granite with large crystals of quartz, feldspar and mica. 结晶花岗岩
Obsidian is nature’s glass. It forms when lava cools quickly on the surface. It is glassy and smooth.玻璃状的,很光滑
Pumice is full of air pockets that were trapped when the lava cooled when it frothed out onto the surface. It is the only rock that floats.浮石是唯一一种可以漂浮的石头,其中充满了气泡。
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Sedimentary Rocks 沉积岩
When mountains are first formed, they are tall and jagged like the Rocky Mountains on the west coast of North America. Over time (millions of years) mountains become old mountains like the Appalachian Mountains on the east coast of the United States. When they are old, they are rounded and much lower. What happens in the meantime is that lots of rock gets worn away due to erosion. Rain, freeze/thaw cycle, wind and running water cause the big mountains to crumble a little bit at a time. 山刚刚形成的时候,很高,棱角分明的。经过很长时间的风吹雨打,山变得矮了很多,更加圆滑。
When rocks are exposed to the elements – air, rain, sun, freeze/thaw cycle, plants – erosion occurs and the little bits of rock worn away get deposited as sediments. Over time, these sediments harden as they get buried by more sediments and turn into sedimentary rocks.
Eventually most of the broken bits of the rock end up in the streams & rivers that flow down from the mountains. These little bits of rock & sand are called sediments. When the water slows down enough, these sediments settle to the bottom of the lake or oceans they run into. Over many years, layers of different rock bits settle at the bottom of lakes and oceans. 那些从山上断裂的岩石碎片顺流而下,被称为沉积物,在湖底洋底堆积。很多年过去,不同的岩石层层积累在水底。
Think of each layer as a page in a book. One piece of paper is not heavy. But a stack of telephone books is very heavy & would squish anything that was underneath. Over time the layers of sand and mud at the bottom of lakes & oceans turned into rocks. These are called Sedimentary rocks. 多年过去,水底的沙子泥土演变成岩石,如书页一般,称作沉积岩。
Some examples of sedimentary rocks are sandstone, shale, marble and jasper. 诸如砂岩、页岩、大理石、玉都是沉积岩。
Sedimentary rocks have fossils in them because plants & animals that have died get covered up by new layers of sediment and are turned into stone. Most of the fossils we find are of plants & animals that lived in the sea. They just settled to the bottom. Other plants & animals died in swamps, marshes or at the edge of lakes and were covered with sediments when the size of the lake got bigger. 沉积岩中往往有化石,因为动植物死了以后会被新的岩层覆盖,成为石头。大多数化石都是海洋生物。也有池塘、沼泽以及生活在湖边的生物的化石。
When large amounts of plants are deposited in sedimentary rocks, then they turn into carbon, which gives us our coal, oil, natural gas and petroleum. A large sea once covered the central part of Canada and the climate was very tropical. In time, sedimentary rocks formed there. That is why we find dinosaur fossils in Alberta and the area is a good source of natural fuels. 当大量的植物堆积在沉寂严重,他们碳化成为煤、石油、天然气。
Sedimentary rocks cover 75% of the earth’s surface. Most of the rocks found on the Earth’s surface is sedimentary even though sedimentary rocks only make up less than 5% of all the rocks that make up Earth.75%的地球表面都是沉积岩,虽然沉积岩只占组成地球岩石的5%。
Sedimentary rocks are usually formed in layers (strata).沉积岩往往是一层层形成的。
There are 6 main kinds of sedimentary rocks depending on the appearance of the rock.从外观来分有六种沉积岩。
Conglomerate rock has rounded rocks (pebbles, boulders) cemented together in a matrix.聚结岩由圆石头(鹅卵石、大圆石)聚结而成。
Sandstone is a soft stone that is made when sand grains cement together. Sometimes the sandstone is deposited in layers of different coloured sand.砂岩是一种比较松散结构的石头,由沙粒聚结而成。有时砂岩会形成不同颜色的岩页。
Shale is clay that has been hardened and turned into rock. It often breaks apart in large flat sections.页岩是泥土硬化后形成的。
Limestone is a rock that contains many fossils and is made of calcium carbonate &/or microscopic shells.石灰石含有很多化石。由碳酸钙构成。
Gypsum, common salt or Epsom salt is found where sea water precipitates the salt as the water evaporates.石膏
Porphory rock is when jagged bits of rock are cemented together in a matrix. |
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