Weathering and erosion Lesson 52 of the geography course of Mova's primary school: 17 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: the lesson at school .
0 Rocks look as if they last for ever, but they are slowly being broken and carried away. 1 Breaking rock where it stands is called weathering; carrying the bits away is called erosion. 2 Leave a full glass bottle of water in the freezer and it can crack, because water grows by about 9% when it freezes. 3 The same thing happens in the cracks of rocks on a frosty mountain, night after night. 4 Rain is slightly acidic and slowly dissolves limestone, and roots and lichens break rock too. 5 Then rivers, wind, ice and gravity carry the pieces off, and drop them when they slow down. 6 Given millions of years, this wins against anything: the old mountains of Scotland were once as high as the Alps. 7 Weathering is the breaking down of rock where it is, by weather, chemicals and living things. 8 Water in cracks freezes and expands by about 9%, pushing the rock apart bit by bit. 9 Rainwater is slightly acidic and slowly dissolves rocks such as limestone. 10 Plant roots grow into cracks and split rocks, and lichens slowly eat into their surface. 11 Erosion is the carrying away of weathered bits of rock by water, wind, ice or gravity. 13 Running water is the most powerful agent of erosion on Earth. 14 In deserts wind blasts sand against rocks and carves strange shapes. 15 When water or wind slows down, it drops what it carries, a process called deposition. 16 Even great mountains are slowly worn down, and old mountains like those of Scotland were once as high as the Alps. 17 Clearing forests and ploughing can make soil erode many times faster than natural rates. ← previous Gemstones and precious metalsnext → Rivers shaping the land↑ back to Geography This page in Markdown → https://md.mova.elamur.ai/free/en/corpora/school/geography/52-weathering-and-erosion/