QUESTIONS. 335 



92. State in full what is said of deposits in rivers and on their bor- 

 ders. 



93. Explain the mode of improving rivers illustrated by Fig. 35. 



94. What is said of deposits in lakes ? State the facts in regard to 

 the Lake of Geneva. What is said of the lakes of our country ? 



95. What is a delta, and why is it so named ? Describe the mode 

 of its formation. What is said of bars and islands formed in connec- 

 tion with deltas? 



96. Why is there no delta at the mouth of the Amazon ? Give in 

 full what is said of the sediment deposited from the Ganges in the 

 Bay of Bengal. What is said of Louisiana, and of the amount of 

 matter brought down by the Mississippi ? 



97. What is said of the extent of deltas? What of the consolida- 

 tion of sediment from rivers into rock ? Give examples of the en- 

 croachment of water upon land. 



98. What is said of the mechanical action of water upon rock? 

 What is said of " Pulpit Rock?" 



99. Illustrate the erosive work which water does by rubbing one 

 solid against another. What is said of pot-holes? Give the state- 

 ment in regard to Niagara Falls. 



100. What is said of the canons of Colorado? What of the erosion 

 by the River Simeto? State in full what is said of the constancy of 

 the action of water in erosions. 



102. How does frost disintegrate rocks? How do the results differ 

 in hard and soft rocks ? What is a talus, and how is it formed ? 

 What is said of the sorting of fragments in a talus ? State in full 

 what is said of the chemical action of water on rocks. 



103. Explain weathering. What is said of the Druidical monu- 

 ments ? What of the weathering of hard and of soft rocks? What 

 of weathering in the soil ? 



104 . Give the statement about the boulder. What is said of the 

 Loggan stones ? How do the present effects of glaciers and icebergs 

 compare with their effects in past ages ? Why is a glacier said to be 

 a river of ice? 



105. Of what is a glacier made ? Wliat are lateral and medial 

 moraines ? Give in full what is said about the termination of a gla- 

 cier. 



107. What is said of the markings and other effects of glaciers? 



108. Describe the formation of terminal moraines. How are ice- 

 bergs produced? What is said of their height? What proportion 

 of an iceberg is above the surface of the water ? 



109. How extensive are some icebergs ? What is stated of their 

 numbers ? What is said of their dropping fragments of rock ? What 

 of their dragging and stranding ? 



