The Dane Niels Stensen (Steno in Latin, 1639-1686) is regarded as a father of geology and stratigraphy. In his De solido intra solidum (“From solids in solids”) in 1669 he constituted the basic stratigraphic principles which are represented today as follows:
- The principle of the lateral extent of rock layers states that rocks that occur in different places, but have exactly the same properties, are from the same rock strata.
- The principle of original horizontality or the principle of horizontal deposition of sediments.
- The principle of superposition or the storage sequence. Sedimentary layers are deposited in a chronological order, from earlier in the lower layers (“down”) to younger in the upper layers (“top”).
Stensens original principles were solely based on the consideration of the already stratified rock. About the process that led to the stratification, he could only guess. He concluded as follows: A precipitation process deposits on the bottom of a liquid saturated with material stratum above stratum. Between the deposition of the strata, the process is interrupted until the last deposited stratum has reached a firm consistency. Later on, Charles Lyell added today’s so called uniformity principle, which states that one can conclude from the current geological processes on the development in the past. As an example Lyell cited deposits resulting from fresh water in the Auvergne (France), which were observed with less than 1 mm thickness. Under the assumption that they constitute annual deposits, 230 m total thickness resulted in several 100,000 years of creation time.
The process of stratification, however, consists of three phases: erosion, transport and deposition. Stensen considered only the final step in his description. He ignored the fact that a flow causes erosion as well as transports material, and thus should not be overlooked in the overall process of deposition.
Otte, Andreas (2011): Stratigraphie und Chronologie. Prinzipien der natürlichen Stratigraphie kritisch hinterfragt; in Zeitensprünge 23 (3) 729-735Print This Page