An important consideration for this study is the usage of “mudstone” and “shale”. Whereas the
term “shale” has been used widely by geologists, it is for some a term associated with fissility, and for
others an indication of fine (sub-cm) bedding (or lamination). It has been suggested that shale should
primarily be used as a field term for fine grained clastic rocks that show fissility, whereas the term
mudstone should be used for any other non-fissile varieties (as cited in Lazar et al., 2010). If, for a
lithostratigraphic group or formation the term “shale” has been used in the past, its use will be continued
as a matter of precedence.