Index fossils are used to date rock strata that would otherwise be very difficult to date. Which of these statements describes a key characteristic of index fossils?

This is what i found “getting into the technicalities, the continental crust has a density of around 3.0 g/cm3 compared to 2.6 g/cm3 of the continental crust. in addition, the continental crust is much thicker than the oceanic crust. the recycling process does not happen to the continental layer.” i hope this you for what your looking for. can you plz mark me brainliest?

When a lake, river or other aquatic  system  becomes  eutrophic, it can have serious negative effects on other organisms like fish, birds and even people.if an algal bloom is so bad that it causes wide-spread death  in  the  water, the organisms that die will all sink to the bottom and start to decompose.