Editing Deep time (section)

== Early theories ==
Early [[geologists]] such as [[Nicolas Steno]] and [[Horace Bénédict de Saussure]] had developed ideas of geological strata forming from water through chemical processes, which [[Abraham Gottlob Werner]] developed into a theory known as [[Neptunism]], envisaging the slow crystallisation of minerals in the ancient oceans of the Earth to form [[rock (geology)|rock]].  Hutton's innovative 1785 theory, based on [[Plutonism]], visualised an endless cyclical process of rocks forming under the sea, being uplifted and tilted, then eroded to form new strata under the sea. In 1788 the sight of [[Hutton's Unconformity]] at Siccar Point convinced Playfair and Hall of this extremely slow cycle, and in that same year Hutton memorably wrote "we find no vestige of a beginning, no prospect of an end".{{sfn|Montgomery|2003}}{{sfn|Rance|1999}}