Chapter 2, Problem 1QRD

To determine

Steno’s principles that were used by William Smith in his studies of strata in England.

Answer to Problem 1QRD

Steno’s principle of superposition is used by William Smith in his studies of strata in England. Based on this principle, he was aware that different types of stratified rock occurred in a definite order and it can be identified on the basis of lithology, the soils they form, and the fossil assemblage it contains.

Explanation of Solution

Three major principles are formulated by Nicholas Steno for the interpretation of sedimentary rock. They are the principle of superposition, the principle of original horizontality, and the principle of original lateral continuity. The principle of superposition describes that in the layered sedimentary rock, the age of individual, undeformed layers decrease from bottom to top. The principle of original horizontality states that the initial deposition of sedimentary rocks occurred horizontally and later they become sloping or folded due to the deformation caused by strong crustal forces after deposition. The principle of original lateral continuity stipulates that the lateral extension of strata occurs in all direction until the thinning of strata, encounter and obstruction or gradually merge into another stratum.

On the basis of studies conducted by William Smith on the order of strata and its fossil assemblage, he published “Strata Identified by Organized Fossils”. This work becomes the original basis for using fossils in correlation or the principle of fossil succession. In addition, Smith prepared the first geological map of England and Wales also.