What two things did 19th century scientists do to determine the relative ages of sedimentary rock all over the world?

They studied fossils (paleontology) and applied the principle that old layers or rock are lying just below young layers

They studied fossils and applied the principle that old layers of rock are below young layers! -. ... What two things did 19th century scientists do to determine the relative ages of sedimentary rock all over the world? ... Making the world better, one answer at a time. ... What are two things that sedimentary rocks change to?

Answer metamorphic rock;