New geographies . also learnedthat they have been formed by the workof running water. We shall next studythe running water that has carved outthe valleys, and that makes the rivers. Every heavy rain causes the water tocollect here and there, and to flow downHow rivers the slopes. At first onlybegin tiny rills are formed, but these unite to make little streams andbrooks. The brooks and small streams,in turn, unite to form rivers. Thus rainalone may cause a river; but as soon asall the rain water runs off, such a riverwould become quite dry if there werenot water from some other source. Eivers u
New geographies . also learnedthat they have been formed by the workof running water. We shall next studythe running water that has carved outthe valleys, and that makes the rivers. Every heavy rain causes the water tocollect here and there, and to flow downHow rivers the slopes. At first onlybegin tiny rills are formed, but these unite to make little streams andbrooks. The brooks and small streams,in turn, unite to form rivers. Thus rainalone may cause a river; but as soon asall the rain water runs off, such a riverwould become quite dry if there werenot water from some other source. Eivers usually have a more regularsupply of water. Some of them, as wehave seen, start in the high mountains,where the snows never entirely meltaway. Others have their beginnings, orsources, in lakes and swamps. It should be remembered, too, thatthere is a great deal of water in theground, for some of it sinks into theearth during every rain. It is thiswater that men find when they digwells. The underground water trickles. Fig. 36. — Icicles formed in winter where water from un-derground slowly oozes out from cracks in the rock. slowly through the soil, and throughcrevices in the rocks (Fig- 36), oftenbubbling forth as a spring, weeks afterit has fallen as rain somewhere rivers have their sources in suchsprings, and most large rivers receivewater along their courses from hun-dreds and even thousands of them. Let us take a journey from the sourceof a river to its lower end, or mouth,and see how it river has its source iaa small spring in the moun-tains, where the clear, coldwater bubbles out of the P^rtground at the base of a rock cliff. How a riverchanges andgrows as itadvances1. Its upper 32 HOME GEOGRAPHY For a short distanceit flows through agrassy meadow (), and is so narrowthat you can easilystep across it. Thewater is so clear thatyou can see the spec-kled trout swimmingabout in a deep holenear one side, or smaller branch, or
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectgeography, bookyear19
