Indeed, if we leave aside Robert Hooke's 'bubble' theory of crater formation a century or so earlier, Herschel might well be regarded as the first 'British' selenographer to argue for a volcanic theory of crater formation--a view that, as we shall see, came to dominate and shape nearly all later British thinking about the nature of the Moon.
One explanation for why the volcanic theory should have been favoured by British observers over impact theory is that the latter inevitably implies an essentially dead Moon, a celestial museum displaying the scars of a violent, but long-gone, past.
Presence of these common clay minerals of volcanogenic derivation under local sedimentation conditions supports the volcanic theory of K-T boundary events (Fig.
The sequence at Anjar contains common clay minerals of volcanic derivation that are explained by local sedimentation conditions and support the volcanic theory on K-T boundary events.
The Ir anomalies in airborne particles emanating from Hawaiian (Olmez et al., 1986) and Kam Chatka (Felitzyn and Vaganov, 1988) volcanoes preserved within the southern ice sheet being contributed by volcanism along Ross Sea (Koeberl, 1989), is evidence to support the volcanic theory. Iridium and other trace metals are enriched in some andesitic volcanic ashes, possibly in the heavy minerals (Goldsmidt, 1954).
The debunking of the volcanic theory
was heartening news for the local people.
As evidence for the volcanic theory
, these scientists have maintained that volcanoes can bring iridium-rich rock from the Earth's mantle to the surface.
Proponents of the volcanic theory have suggested that the Deccan eruptions caused the K-T extinctions by spewing out sulfur and other volcanic material that darkened the skies, cooled the planet and produced acid rain.
Courtillot concedes that the shocked quartz remains a problem for the volcanic theory, but Officer disagrees.
As for the K-T extinction, he stands by the volcanic theory.
Acid rain also plays a role in the volcanic theory
of the origin of mass extinctions, whose strongest proponent, Charles B.
In support of the volcanic theory
, on the other hand, Officer and Drake believe there is direct evidence for large-scale movement of magma to the surface around K/T time.