Desert formation 沙漠的形成(1)
The deserts, which already occupy approximately a fourth of the Earth’s surface, have in recent decades been increasing at an alarming at an alarming pace. The expansion of desertlike conditions into areas where they did not previously exist is called desertification. It has been estimated that an additional one-fourth of the Earth’s land surface is threatened by this process.
Desertification is accomplished primarily through the loss of stabilizing natural vegetation and the subsequent accelerated erosion of the soil by wind and water. In some cases the loose soil is blown completely away, leaving a stony surface. In other cases, the finer particles may be removed, while the sand-sized particles are accumulated to form mobile hills or ridges of sand.
Even in the areas that retain a soil cover, the reduction of vegetation typically results in the loss of the soil’s ability to absorb substantial quantities of water. The impact of raindrops on the loose soil tends to transfer fine clay particles into the tiniest soil spaces, sealing them and producing a surface that allows very little water penetration. Water absorption is greatly reduced; consequently runoff is increased, resulting in accelerated erosion rates. The gradual drying of the soil caused by its diminished ability to absorb water results in the further loss of vegetation, so that a cycle of progressive surface deterioration is established.
(* Highlight 的單字是有解說的單字，非問題。)
單字解說：
1) occupy (V.) 佔據（空間或時間）； 使（某人）忙於；使（某人）感興趣 ； （軍隊或一夥人）佔領
2) approximately (Adv.) 大約
3) expansion (N.) （尺寸、數量或重要性的）擴大
4) conditions (N.) 物質條件；情況；實際環境
5) desertification (N.) 沙漠化
6) estimate (N. / V. ) 估計；估算
7) threaten (V.) 威脅，恐嚇
8) process (N. / V. ) 過程；步驟； 處理；辦理
9) accomplish (V.) 完成；實現；達到；做到
10) primarily (Adv.) 主要地
11) stabilize (V.) 穩定下來 ；使穩固
12) vegetation (N.) 植被
13) subsequent (Adj.) 接著的
14) accelerate (V.) 加速 ； （使）加快，（使）增速；促進；提前，（促使）早日發生
15) erosion (N.) 侵蝕[作用]
16) the soil 耕作，務農
17) accumulate (V.) 積累；積聚；積攢； 逐漸增加
18) reduction (N.) 減少；減；縮影
留言列表
