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