Example of Relative
Geological Time
Roadcut through a mountainous area
What is present?
Three inclined sedimentary layers (sandstone,
shale, and limestone – intruded by a granite dike.
Sedimentary layers must have been tilted.
Was the granite dike intruded before or after the tilting?
Can’t tell from this diagram.
Finally – don’t forget about the present-day landscape – must have
had uplift and erosion to form the present-day landscape. The sedimentary
rocks must have been buried to become lithified.
Therefore, the final sequence in order of relative age is:
Uplift and erosion (youngest)
Intrusion of granite dike (or tilting)
Tilting of beds (or granite dike)
Deposition of limestone
Deposition of shale
Deposition of sandstone (oldest)