Angular unconformity: a discordant surface of contact between the deposits of two episodes of sedimentation in which the older, underlying strata have undergone folding, uplift, and erosion before the deposition of the younger sediments, so that the younger strata truncate the older.

Michael Allaby, ed., A Dictionary of Earth Sciences, 3rd ed. (Oxford: Oxford University Press, 2008)

Angular Unconformity shows us a life's work in cross-section, a restless and humane intelligence, ever searching, ever shifting, finding meaning in our blink-of-an-eye existence...