Soil, a Component of the Rock Cycle, can Lead to an Appreciation of Deep Time

The rock cycle is an organizational principle for the sequence of topics in geology textbooks. However, while weathering and soils are topics usually well treated in the text, not featured in pictorial illustrations of the rock cycle is the product of weathering which is SOIL. Pedagogically this omission is regrettable as lost is a ready way to inculcate a true feeling for the length of geological time. In human experience, the rate of erosion and transportation of sediments by running water can be fast. So accumulation of sediments, as in a fan deposit, or as a delta, need not imply a great length of time. However, easily understood is that the rate of delivery cannot exceed the rate of supply. From an area blanketed by soil, the rate of supply cannot exceed the rate at which bedrock there weathers to soil. Rock such as granite weathers with geological slowness, imperceptibly so for granite monuments, to quartz sand and clay. With that emphasized, the vastness of geological time can then be understood from the very bulk of known quartz sandstone and shale sedimentary formations.