Deformation of Graptolites and Sandstones in Slates from Victoria, Australia

Publisher Website
Google Scholar
Abstract
The deformation of fossils in slates has been studied by many investigators, generally with a view to obtaining data on the strain to which the enclosing rock has been subjected. In the examples previously dealt with it has been necessary to assume an arbitrary length for one of the three principal axes of strain, since the absolute dimensions of the fossils before deformation were unknown. With graptolites, however, the spacing of thecae is a specific characteristic, and, since under favourable circumstances the species of a deformed specimen may be determined by a palaeontologist familiar with the graptolite faunas of a district, comparison of the thecal spacing with that normally characteristic of the species can give a measure of the deformation in absolute units. In some instances generic determination may be sufficient for the purpose. Furthermore, since graptolite rhabdosomes are delicate structures it is reasonable to assume that the amount of deformation they indicate closely approximates to that for the rock matrix as a whole, whereas it is doubtful if such an assumption can be made with more massive fossils. Unfortunately, however, graptolites are so thin that they afford practically only a two-dimensional picture, although it is possible to obtain some data from cross-sections.

This publication has 6 references indexed in Scilit: