so that you can age determination of sedimentary stones, we have to index fossil the fossil which major geographical circulation and low time period. Paleontologic information supports the index fossil of every band of paleo-organisms.
A lot of stratigraphy and paleontology documents enable you to figure out the chronilogical age of sedimentary stones. I would suggest the USGS website website link which explain to you need for fossils and stratigraphy in your concern.
Igneous intrusions form whenever magma breaks via a layer of stone from beneath, or lava flows straight down from above. They can permeate levels of sedimentary stone.