66. What is the difference between lacustrine and fluvio-marine
deposits? What is a _delta_?
67. Describe the geological action of frost. Describe the geological
action of river-ice.
68. What are _glaciers_? What thickness do they attain in the Alps?
What is their rate of motion? What are _crevasses_, and how do they
originate? What are _superficial moraines_? What are _terminal
moraines_? What changes does a glacier effect upon its bed, and how
are these modifications produced? What is the character of a glacial
river? What is the origin of _icebergs_? How is the general absence of
blocks and stones in Greenland icebergs to be explained? What is the
nature of a submarine terminal moraine? What is the _ice-foot_? What
is the chief agent in distributing erratic stones and blocks over the
sea-bottom? What effect upon the sea-bed must stranding icebergs
produce?
69. What are some of the chemical compounds held in solution in
sea-water? Which of these go to form the shells and skeletons of
marine animals?
70. Describe the action of breakers on a sea-coast. How does frost aid
the wasting action of breakers? What effect has the nature of the
rocks in the production of inequalities in a coast-line? Upon what
part of the sea-bottom does the material derived by the action of the
breakers chiefly accumulate? What effect have the tides and ocean
currents in the distribution of sediment?
71. What is the general rule as regards fine-grained and
coarse-grained deposits? Mention a partial exception to this rule.
What effect have tidal currents in shallow seas?
72. How are rocks disintegrated through the action of plants? What is
peat? What may be inferred from the occurrence of shell-marl
underneath peat? What does the appearance of roots and trunks of
trees, and of remains of land animals under peat, indicate?