What does a relative time scale use to measure the age of the Earth?
The relative time scale uses geologic features to build a sequence of events. It relies on several geologic principles to do this. Original horizontality – water laid sediments are originally deposited in flat layers. If they’ve been uplifted or folded, then the disruption came later. Cross-cutting relationships – a formation that has something cutting across it is older than what cuts across it. Superposition – older deposits are lower in the sequence with younger deposits progressing upward. This is for undisturbed formations (that is, they haven’t been overturned). Faunal succession – more complex and diverse organism are found in younger formations than simpler forms of life. Index fossils are used to correlate formations from different regions. Uniformitarianism – “The present is the key to the past.” What that means is that processes that operate today operated in the same way in the geologic past, and by studying how things work today we can figure out how older features were cr
