unconformity

The sites include familiar ones, such as the Grand Canyon’s “great unconformity,” a billion-year gap in the rock record erased by erosion.

An “unconformity” is the geological term for “a discontinuity in the deposition of sediment,” in Raffles’s words.

It echoes James Playfair’s description of the “abyss of time” he glimpsed while viewing a strata unconformity at Siccar Point in 1788, when geology was first emerging as a science.

An unconformity: At Mount Stimson, the rover identified from sol 980 a thick sandstone unit overlying the lake deposits, separated by a geological feature called an unconformity.

These desert-formed sandstones sit above an unconformity, and this suggests that after a long period with a humid climate, the climate became drier and wind became the dominant agent shaping the environment at Gale Crater.