Ash and lava fragments that cascade down the sides of a volcano eventually settle and lithify to form an extrusive igneous rock called

The appropriate response is Welded Tuff. It is a pyroclastic shake, of any root, that was adequately hot at the season of testimony to weld together. Entirely, if the stone contains scattered pea-sized pieces or fiamme in it, it is known as a welded lapilli-tuff.

The investiture controversy began as a power struggle between pope gregory vii (1072–85) and henry iv, holy roman emperor (1056–1106).[2] a brief but significant struggle over investiture also occurred between henry i of england and pope paschal ii in the years 1103 to 1107, and the issue played a minor role in the struggles between church and state in france, as well.by undercutting the imperial power established by the salian emperors, the controversy led to nearly 50 years of civil war in germany, and the triumph of the great dukes and abbots. imperial power was finally re-established under the hohenstaufen dynasty. historian norman cantor: