Running Water - The Changing Earth: Exploring Geology and Evolution - page 326

7. The recycling of water from the oceans to the land and
back to the oceans is known as the
a. ______ superposed drainage;
b. ______ erosion capacity;
c. ______ hydrologic cycle;
d. ______ infi ltration rate;
e. ______ lateral accretion depth.
8. A deposit usually composed of sand that is deposited
on the gently sloping side of a river meander is called
a. ______ an oxbow lake;
b. ______ the dissolved load;
c. ______ a fl oodplain;
d. ______ a delta;
e. ______ a point bar.
9. The suspended load of a stream is made up of
a. ______ silt and clay;
b. ______ dissolved material;
c. ______ sand and gravel;
d. ______ organic matter;
e. ______ runoff.
10. Dividing the vertical drop of a stream by the horizontal
distance it fl ows gives the
a. ______ discharge;
b. ______ alluvial capacity;
c. ______ gradient;
d. ______ profi le of equilibrium;
e. ______ velocity.

11. Calculate the daily discharge of a river 148 m wide and
2.6 m deep, with a fl ow velocity of 0.3 m/sec.
12. Diagram and describe how an ideal small delta forms.
13. Explain how the hydrologic cycle works.
14. Why is Earth the only terrestrial planet with abundant
surface water?
15. Describe the processes whereby running water erodes.
16. The discharge of most rivers and streams increases
downstream, but in a few cases, it actually decreases
and they eventually disappear. Why? Give an example.
17. Explain how stream terraces form and what they indi-
cate about the dynamics of a stream or river system.
18. About 10.75 km 3 of sediment erodes from the con-
tinents each year, and the volume of the continents
above sea level is 93,000,000 km 3 . Thus the conti-
nents should erode to sea level in just over 8,600,000
years. The fi gures given are reasonably accurate, but
something is seriously wrong with the conclusion
that the continents will be leveled in so short a time.
Explain.
19. A river with headwaters 2000 m above sea level fl ows
1500 km to the sea. What is its gradient? Do you think
that your calculated gradient is valid for all segments of
this river? Explain
20. Explain how a superposed stream develops. Also de-
scribe the landforms that result from superposition.