CHAPTER IX. ON THE GREAT RING-FORMATIONS NOT MANIFESTLY VOLCANIC. 117 Absence of Central Cones—Vast Diameters—Difficult of Explanation—Hooke’s Idea—Suggested Cause of True Circularity—Scrope’s Hypothesis of Terrestrial Tumescences—Rozet’s Tourbillonic Theory—Dana’s Ebullition Theory CHAPTER X. PEAKS AND MOUNTAIN RANGES. 124 Paucity of extensive Mountain Systems on Moon—Contrast with Earth—Lunar Mountains found in less disturbed Regions—Lunar Apennines, Caucasus, and Alps—Valley of Alps—“Crag and Tail” Contour—Isolated Peaks—How produced—Analogy from Freezing Fountain—Terrestrial Counterparts and their Explanation by Scrope—Blowing Cone on Teneriffe—Comparative Gentleness of Mountain-forming Action—Relation between Mountain Systems and Crater Systems—Wrinkle Ridges CHAPTER XI. CRACKS AND RADIATING STREAKS. 133 Description—Divergence from Focal Craters—Experimental Explanation of their Cause—Radial Cracking of Crust—Outflow of Matter therefrom—Analogy from “Starred” Ice—No Shadows cast by Streaks—Their probable Slight Elevation—Open Cracks—Great Numbers—Length—Depth—In-fallen Fragments—Shrinkage a Cause of Cracks—Lateness of their Production CHAPTER XII. COLOUR AND BRIGHTNESS OF LUNAR DETAILS: CHRONOLOGY OF FORMATIONS, AND FINALITY OF EXISTING FEATURES. 143 Absence of Conspicuous Colour—Slight Tints of “Seas”—Cause—Probable Variety of Tints in small Patches—Diversity of Brightness of Details—Most Conspicuous at Full Moon—Classification of Shades—Exaggerated Contrasts in Photographs—Brightest Portions probably the latest formed—Chronology of Formations—Large Craters older than Small—Mountains older than Craters—Bright Streaks comparatively recent—Cracks most recent of all Features—Question of existing Change—Evidence from Observation—Paucity of such Evidence—Supposed Case of _Linné_—Theoretical Discussion—Relative Cooling Tendencies of Earth and Moon—Earth nearly assumed its final Condition—Moon probably cooled Ages upon Ages ago—Possible slight Changes from Solar Heating—Disintegrating Action