geology relative time

Steno

realized earths history contains a chronological history of geologic events.

Sandstone

is younger than shale because the pieces of shale eroded as the was deposited.

Nonconformity

: a boundary between non- sedimentary rocks (below) and sedimentary rocks (above)

Angular unconformity

: a boundary between two sequences of sedimentary rocks where the underlying ones have been tilted (or folded) and eroded prior to the deposition of the younger ones.

Disconformity

: a boundary between two sequences of sedimentary rocks where the underlying ones have been eroded (but not tilted) prior to the deposition of the younger ones.

angular unconformity

a boundary between two sequences of sedimentary rocks where the underlying ones have been tilted (or folded) and eroded prior to the deposition of the younger ones

disconformity

a boundary between two sequences of sedimentary rocks where the underlying ones have been eroded (but not tilted) prior to the deposition of the younger ones