It might be expected that the earth’s surface would be studied before the deeper crust. This may be true if the word “studied” is not used critically. That the surface would be observed, talked about, written about, and even to some degree thought about, is a fairly safe expectation and seems to agree with the historical facts. When it comes to what may be called study in a scientific sense, we find that things taken for granted when civilization was young are about the last things to be investigated critically.
The result was that mineralogy, paleontology, and even microscopic petrography began their careers as critical sciences in advance of systematic physiography. It was only when present-day processes became the key to unlock the past that critical study was really demanded. This was not much before the nineteenth century. And it was not until the late decades of that century . . .