EESA06H3 Lecture 8: Lecture 8
21 Apr 2018
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Document Summary
Stratigraphy: the sub-discipline of geology which is concerned with age of rocks. Study of earth history as revealed by strata. When crust is subsiding (crust to be sinking over broad areas called basins), it floods with water and we can accumulate sediments: the su(cid:271)side(cid:374)(cid:272)e of earth(cid:859)s (cid:272)rust (cid:449)hi(cid:272)h allo(cid:449)s depositio(cid:374) of sedi(cid:373)e(cid:374)t o(cid:448)er (cid:271)road areas (cid:894)sedimentary basins) It results in erosion and removal of sediment and rock. Conformable succession: layers sit on each other without any major breaks. Unconformable succession: major time breaks within the succession. Layers on top are sitting unconformably on the rocks underneath. Disconformities (d) mark pauses in sedimentation within an otherwise conformable succession of strata. Unconformities (u) mark episodes of uplift, erosion and non-deposition. More gaps than record: the amount of time that(cid:859)s re(cid:272)order (cid:271)(cid:455) the ro(cid:272)ks is less tha(cid:374) the ti(cid:373)e re(cid:272)order (cid:271)(cid:455) disconformities. The amount of lost time which is recorded by the gaps (disconformities), is (cid:373)ore tha(cid:374) (cid:449)hat(cid:859)s record in the rock.
