Discusses CL’s refutation of CD’s concept of "craters of elevation" and CL’s new concept of "craters of denudation". Mentions examples of such craters. Admits that his own concept of these craters was unsatisfactory. Urges CL to publish article ["On craters of denudation", Q. J. Geol. Soc. Lond. 6 (1850): 207–34].

Criticises Élie de Beaumont’s view of a right angle junction of a stream of lava and a dike.

Mentions his misgivings in voting to recommend J. D. Forbes for Royal Medal.

Notes Daniel Sharpe’s work on mica schist.

Discusses J. D. Dana’s Geology [1849]. Pleased that the part on corals confirms his views [Coral reefs (1842)]. Discusses Dana’s observation that in Sandwich Islands lava streams often join dikes at right angles with no cone. Retracts earlier denial of this possibility. Criticises Dana’s view of Australian valleys.

Continues discussion of Dana’s Geology [1849]. Comments on dikes of Hawaiian volcanoes and Dana’s view of craters of denudation. Compares role of sea and rivers in forming valleys. Criticises Dana’s treatment of CD’s account of coral reefs.