19. Name some typical Eolian rocks, and tell where they occur.
20. How do stalactites and stalagmites occur? What is siliceous sinter, and how does it occur? How does rock-salt occur?
21. Mention some of the varieties of limestone. What is cornstone? What is the composition of dolomite?
22. Name some of the varieties of coal.
23. What is quartzite?
24. Describe clay-slate.
25. Mention some altered limestones.
26. What are schists? Name and give the mineralogical composition of three schists.
27. What is the general character of metamorphic rocks?