|Nicolas Steno stratigraphy|
- To explain how a shark’s tooth had the same shape
- as fossils known as glossopetræ, “tongue-stones,”
- Niels Stensen, known as Nicolas Steno, took a year to study
- how fossils could be derived from living things,
- embedded in stone, and raised up into mountains.
- Fabio Colonna had established that glossopetræ
- had organic origins; Steno explained how this happened
- and extended this by describing how sedimentary rocks
- formed in layers, were broken, tilted, covered, and uplifted.
- “At the time when any given stratum was being formed,
- all the matter resting upon it was fluid, and, therefore,
- at the time when the lower stratum was being formed,
- none of the upper strata existed.”
- “Hence it follows that strata,
- either perpendicular to the horizon or inclined toward it,
- were at one time parallel to the horizon.”
- “Materials forming any stratum were continuous over the surface of the earth
- unless some other solid bodies stood in the way.”
- “If a body or discontinuity cuts across a stratum,
- it must have formed after that stratum.”
Time and logic
- Logic and direct observation
- were hardly to be expected
- in Steno’s time; his makes it clear
- he was a man of genius.
- Take a close look and work it out
- one step at a time. Time means
- nothing; what is logic? Only that each thing
- must happen before the next.