becoming known as “the Father of English Geology.” Using Steno’s principles, a relative time scale was developed in the nineteenth century with names derived from areas studied and characteristics of the rocks in those areas.
The figure in section 7.1 shows the names applied to units and subunits of the Geologic Time Scale.
The discovery of radioactive An atom that has different number of neutrons but the same number of protons.
CC BY-SA 3.0], via Wikimedia Commons' src=" alt="The canyon is shown with many layers" width="3600" height="2400" srcset=" sizes="(max-width: 709px) 85vw, (max-width: 909px) 67vw, (max-width: 1362px) 62vw, 840px"/The Geologic Time Scale and the basic outline of Earth history were worked out long before we had any scientific means of assigning numerical units of age like years to events of Earth history.
Working out Earth history depended on realizing some key principles of relative time.
The pinching Temple Butte is the easiest to see, but even between the Muav and Redwall, there is an Wikimedia Commons' src=" alt="The rocks are mostly red." width="300" height="224" srcset=" sizes="(max-width: 300px) 85vw, 300px"/The theory that the outer layer of the Earth (the lithosphere) is broken in several plates, and these plates move relative to one another, causing the major topographic features of Earth (e.g.
mountains, oceans) and most earthquakes and volcanoes.