穿时是沉积地层的基本属性,其根本原因是地层的形成作用,即沉积作用本身。有沉积作用就有穿时(侧向加积);或者小范围内不穿时但大范围内必穿时(纵向加积)。海水进退只能影响穿时的具体形式而不是穿时的本质原因或必要条件。板块的运移和增生不仅造成了沉积地层的穿时,还造成了火山地层的穿时。这种穿时与沉积作用直接引起的穿时有本质不同,本文称之为构造穿时。

Diachroneity is a substantial character of sedimentary strata and its essential cause is sedimentation. Where there is sedimentation there will be diachroneity (lateral accumulation) ; even if diachroneity does not exist in limited areas with vertical accumulation, it must exist in relatively extended scale of such sedimentation. Marine transgression or regression could define the type diachroneity but is not the necessary factor or essential cause for diachroneity.The movement and accretion of plates have caused the diachroneity not only of sedimentary strata but also of volcanogenic strata. This kind of diachroneity has nothing to do with sedimentation and is tectonic diachroneity in this paper.