1·As it crashed down the steep mountainside like a gigantic snowplough, it swept up trees, boulders and tons of topsoil, and completely crushed and destroyed the six villages that lay in its path.
它像一台巨大的扫雪机一样冲下陡峭的山坡，卷走了树木、巨石和成吨的表土，将沿途的六个村庄彻底摧毁。
2·Calm and peaceful for most of the year, the Nile used to flood annually, thereby creating, irrigating and carrying new topsoil to the nearby farmland, on which ancient Egypt depended for livelihood.
尼罗河在一年的大部分时间里平静而祥和，过去每年都会泛滥，从而创造，灌溉并把新的表土运到附近的农田，古埃及赖以生存。
3·Angkor may have suffered problems common to modern times, including deforestation, overpopulation, topsoil degradation and erosion.
吴哥可能已经遭受过和现代相同的问题，包括滥伐森林，人口过剩，表土退化和侵蚀。
4·One major problem is that degraded soils become compacted and so absorb less water, which then tends to run off the surface, taking topsoil with it.
一个主要的问题是，退化的土壤变得密实，造成吸水量减少，从而导致水从地表流失并将表土带走。
5·Excavation generally starts with the separate stripping of the organic topsoil, which is later reused for landscaping around the new structure.
通常土方发掘先将有机表土分别挖除，竣工后还可将其用于新修建物周围景观工程。