Flood geology (also creation geology or diluvial geology) is the attempt to interpret and reconcile geological features of the Earth in accordance with a literal belief in the global flood described in Genesis 6–8. In the early 19th century, diluvial geologists hypothesized that specific surface features provided evidence of a worldwide flood which had followed earlier geological eras; after further investigation they agreed that these features resulted from local floods or from glaciers. In the 20th century, young-Earth creationists revived flood geology as an overarching concept in their opposition to evolution, assuming a recent six-day Creation and cataclysmic geological changes during the biblical flood, and incorporating creationist explanations of the sequences of rock strata.