A geologist finds a layer of rock with marine invertebrate fossils and
below that a layer with only land dwelling animal fossils which does
this most likely indicate about artys past in this area?

The nuclear decay of radioactive isotopes is a process that behaves in a clock-like fashion and is thus a useful tool for determining the absolute age of rocks. Radioactive decay is the process by which a “parent” isotope changes into a “daughter” isotope.

Explanation:Together with stratigraphic principles, radiometric dating methods are used in geochronology to establish the geologic time scale. Among the best-known techniques are radiocarbon dating, potassium–argon dating and uranium–lead dating.

answer; professor;

the answer would more than likely a.)falling crop prices  

hope the answer is right and ,either way have a nice day.