Answer:
1) Steno's principles are important because, he deduced that rocks were laid down in vertical order just as sediments are laid down today, under water.
2) Scientists use a technique called radiocarbon dating to find out the age of the fossils.
3) Uniformitarianism is the principle that we can infer long term trends from those we have observed over a short period. In its stronger sense it claims that processes operating in the present can account, by extrapolation over long periods, for the evolution of the earth and life.
4) The geologic record is the history of Earth as recorded in the rocks that make up its crust. ... The way these strata are arranged and what fossils are in them give scientists clues about what Earth was like billions of years ago.
5) Fossils are the remains or traces of ancient life that are usually buried in rocks. Examples include bones, teeth, shells, leaf impressions, nests, and footprints. This evidence reveals what our planet was like long ago. Fossils also show how animals changed over time and how they are related to one another.
6) By studying rocks up close, we can learn all sorts of things about Earth's layers, including how old they are (how long ago that layer of the Earth formed), what type of rocks make up each layer (and what the properties of those rock types are), and what minerals form the rocks in each layer
7) The geologic time scale was developed after scientists observed changes in the fossils going from oldest to youngest sedimentary rocks.
8) Igneous rocks are formed from melted rock deep inside the Earth. Sedimentary rocks are formed from layers of sand, silt, dead plants, and animal skeletons. Metamorphic rocks formed from other rocks that are changed by heat and pressure underground.
9) Sedimentary rocks are formed when sediment is deposited out of air, ice, wind, gravity, or water flows carrying the particles in suspension
