I have added these posts on volcanics because of their importance to sedimentary basins and basin stratigraphy – whether as lava flows, primary volcaniclastics derived from ash columns, fire fountains, autobrecciation of lava, or pyroclastic flows and surges, or secondary volcaniclastic processes that rework and redistribute primary deposits (e.g. lahars). R.V. Fisher, an icon of volcanology once said something like – when fragmented magma exits an eruption vent it is volcanic, and when it comes down it is sedimentary (not an exact quote – but close enough). I like this, because (1) I have always enjoyed looking at volcanic rocks of one sort or another, and (2), as a sedimentologist it justifies any time I might have spent looking at volcanic rocks. The posts here show some attributes of volcanic rocks encountered in the field. The collection of images is by no means encyclopedic, but hopefully they are useful.
Volcanics in outcrop: Lava flows
Volcanics in outcrop: Secondary volcaniclastics
Mount St. Helens: 40th Anniversary Not outcrop, but an important and probably one of the most analyzed events
Volcanics in outcrop: Pyroclastic fall deposits
Volcanics in outcrop: Pyroclastic density currents
Ignimbrites in outcrop and thin section
Accretionary aggregates and accretionary lapilli
Class 5; The Toba eruption – how a super volcano almost stopped humanity in its tracks
