146 NATURE-STUDY LESSONS. 



6. If the stream opens into a pool or pond or lake, 

 observe what kinds of materials are deposited near the 

 mouth of the stream and what kinds are carried into the 

 deeper parts of the water. 



See experiment under Soil, page 154. 



7. (a) Account for the deposition of coarse gravel, 



fine gravel, sand and silt, where you find them 

 in a stream or pond. 

 (d) Where has each of these classes of material 

 come from ? 



8. Observe how each successive rainstorm deepens 

 and widens the bed where the water flows. 



9. After every rainstorm, why are the streams of 

 water muddy ? 



If the stream is a permanent one and large it is called a river ; the bed 

 wherein the water flows is its channel ; the land on both sides which con- 

 fines the water to its channel are the banks ; and the country through 

 which the stream flows is a valley. 



10. («) Observe how the river makes its way through 



the valley. 

 (U) In what part of its course does the water flow 



most rapidly? 

 {c) Where most slowly ? 

 (d) Upon what does the velocity of a stream 



depend ? 

 {e) In which part is the water deepest .'' 

 (/") In which part most shallow ? 

 (<?") What connection is there between the rate of 



flowing and the depth of the water ? 



11. Is the stream always of the same width? Account 

 for any differences in width. 



