As is the case with most petrological terms the exact connotation is not very strictly defined; most authors allow that accessory minerals such as felspar, garnet, augite and quartz may be present in variable and often considerable amount.
An interesting and orderly petrological sequence of Tertiary igneous rocks has been determined.
Believing the black rock of the Schlossberg at Stolpen to be the same as Pliny's basalt, he applied this name to it, and thus originated a petrological term which has been permanently incorporated in the vocabulary of science.
The text-books on this subject are so numerous and accessible, that a very brief account of the volcanic rocks is all that need be given here for the purposes of reference by readers not familiar with petrological details.
It is a rock of peculiar interest from the fact that it is almost unique in the British Islands, and has its petrological counterpart rather amongst the volcanic hills of the Siebengebirge than elsewhere.
The rocks of the Jurassic system present great petrological diversity.
The petrological characters will be found more fully discussed in Chapter XXI.
Most of thepetrological details are dealt with under their respective sections; but it has been found necessary also to frequently refer to them in this connection.
The general petrological characters of the principal summit of Mount Ngala point to its high antiquity as a volcanic mountain.
Mr Harker is supplementing these descriptions by a series of petrological memoirs on Darwin's specimens, the first of which appeared in the "Geological Magazine" for March, 1907.
Of course in these days, since the application of the microscope to the study of rocks in thin sections, Darwin's nomenclature and descriptions of the petrological characters of the lavas appear to us somewhat crude.
A geological examination of the ground would show that the features in question were everywhere the result of denudation, guided by the petrological character and geological structure of the rocks.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "petrological" in a variety of sentences. We hope that you will now be able to make sentences using this word.
