Which type of fossil is useful for correlating the rock strata (layers) in which they are found?
O staple fossil
O variable fossil
O index fossil
O directional fossil

The difference(s) between the grand canyon and valles marineris is/are: (a) the grand canyon was formed by water, but valles marineris was not. (a) valles marineris is much longer than the grand canyon. (c) valles marineris is much wider than the grand canyon. (d) valles marineris has large volcanoes near it. all of the above

Compare demographic and environmental effects of the columbian

[fw.02]sinkholes are often formed as a result of the actions of. a.heat on recharge b.pressure on aquifers c.acid in groundwater d.minerals in hot springs