在一些山崖上或河流两岸的陡壁上,可以观察到岩石一层又一层地重叠着,并且向四周延伸,这就是“地层”。地层是怎样形成的呢? 原来,地壳——地球的表层永不停息地运动着,叫地壳运动。它往往表现为地表某些地区地势的相对上升和相邻地区地势的相对下降。上升的或者地势相对较高的大陆、高山等地区,长年累月经受风化、侵蚀等作用,原有物质不断被破坏,产生了大量碎石、泥砂及溶解于水的化学物质。这些物质因自身的重力和风或流水的挟带,被搬运到下降的或地势相对较低的山脚、洞穴和江湖河海里,一层一层地沉积下来。沉积物起初很松散,有大量孔隙和水分。随着沉积物层次的 On some cliffs or on the steep sides of the river, one can see that the rocks overlap one after another and extend all around, which is called “strata.” How is the formation formed? It turned out that the crust - the earth’s surface never stops moving, called the crust movement. It often manifests itself in the relative rise of the terrain in some areas of the Earth’s surface and the relative decline of the terrain in the neighboring areas. Ascending or topographic continents such as the mainland and alpine areas have been subjected to weathering and erosion over many years. The original materials have been continuously destroyed, resulting in a large amount of gravel, silt and chemicals dissolved in water. These materials, due to their own gravity and wind or water entrainment, are transported to the descending or relatively low-lying foothills, caves and rivers and lakes and are deposited layer by layer. The sediment was initially loose with a lot of pores and moisture. With the sediment level