Evcp: Volcaniclastic rocks—Lithic and feldspatholithic volcanic to tuffaceous sandstone, silty sandstone, and siltstone containing some interbeds of volcanic (pebble) conglomerate, tuff, lapilli tuff, breccia, shale, organic tuffaceous siltstone, and coal; leaf fossils and petrified wood common; generally light yellowish brown to very pale brown to light bluish gray to greenish gray sandstone, with some dark red to reddish brown to grayish black siltstone.
https://github.com/davepinch/pinchy.cc/blob/master/content/topics/places/waterfalls/marckworth-falls/marckworth-falls.md
