Hot melted rock called lava flows from volcanoes and then cools and hardens into crystals, forming a layer of rock. Great rivers of ice called glaciers creep down from mountains, carrying rocks and soil with them. When the glaciers melt, they leave the rocks and soil behind them on the lowlands or in the ocean. Water also changes the Earth. Waves along the shores wash away the land gradually and continuously.
Rivers eat away mountains piece by piece and carry the mud and sand to the oceans.
The movement of water across the ocean floor spreads layers of mud and sand that gradually harden into stone. Rivers also carry soil to lowlands, where it creates rich farmland. We'd like to hear from you. Click here to submit your comments.