THE ATMOSPHERE AS A GEOLOGICAL AGENT.
+The Atmosphere as a Direct Agency+ 21
I. _Mechanical Work_ 21
Transportation and deposition of dust, 22. Transportation
and deposition of sand, 25. Formation of dunes, 26. Shapes
of dunes, 26. The topographic map, 30. Topography of dune
areas, 32. Migration of dunes, 33. Distribution of dunes, 35.
Wind ripples, 37. Abrasion by the wind, 38. Effects of wind
on plants, 40. Indirect effects of the wind, 41.
II. _Chemical Work_ 41
Precipitation from solution, 41. Oxidation, 42. Carbonation,
43. Other chemical changes, 43. Conditions favorable for
chemical changes, 43.
+The Atmosphere as a Conditioning Agency+ 43
I. _Temperature Effects_ 44
II. _Evaporation and Precipitation_ 50
III. _Effects of Electricity._ 52
+Summary+ 54