The trachytes occupy a position between the pitchstone lavas on the one hand, and the andesites and granophyres on the other.
The trachytes and basalts of Popayan are separated from the system of the volcanoes of Quito by the mica-slates of Almaguer; the volcanoes of Quito from the trachytes of Assuay by the gneiss of Condorasta and Guasunto.
A similar disengagement of vapours, joined to the elastic force of the gases, which penetrate strata softened and raised up, appears sometimes to have given great extent to the caverns found in trachytesor trappean porphyries.
The two principal members of the Plutonic family of rocks are Granite and Syenite, each of which, with their varieties, bear very much the same relation to each other as the trachytes bear to the basalts.
It is highly probable that, between the oldest trachytes of Tuscany and the newest rocks in the neighbourhood of Naples, a series of volcanic products might be detected of every age from the Older Pliocene to the historical epoch.
Although quartz is not a necessary ingredient in the composition of this rock, it is very frequently present, and the quartz trachytes are very largely developed in many volcanic districts.
In this respect the trachytes differ entirely from the members of the Basaltic family, and are more nearly allied to the granites.
The same traveller supposes, although he found no limestone or trace of fossils in any of the rocks of Teneriffe, that the alternating trachytes and trachytic conglomerates originated beneath the sea.
From Loxa to Popayan these Cordilleras are composed alternately of trachytesand primitive rocks.
The porphyries issue (like the trachytes of the Andes) in domes from the bosom of intermediary rocks.
The alteration observed in several of these oligoclase-trachytes is restricted chiefly to the interstitial glass in which secondary quartz and at times calcite and viridite are developed.
The pitchstone or vitreous form of these trachytes is displayed in the blocks of an agglomerate-tuff between Tawaki and Mount Thuku.
Exposure of altered trachytesand quartz-porphyries at its base, 215.
Next to the pumice-tuffs, massive quartz-porphyries and oligoclase-trachytes are the characteristic rocks.
The difference between the oligoclase-trachytes in various localities appears to be mainly concerned with the varying degrees of crystallisation.
It is certain that the trachytes which form the principal portions of the rocks including gold, are now almost universally regarded as of igneous or volcanic origin.
Finally, if it be true that the ancients worked mines of gold in the island of Ischia, it would be another example, and a very remarkable one, of the presence of this metal in trachytes of an origin evidently volcanic.
Weise read Wisse ----6 from bottom, for trachytes of Hungary read trachytes out of Hungary xlii.
These three transverse chains have no active volcanoes; we know not whether the most southern, like the two others, be destitute of trachytes or trap-porphyry.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "trachytes" in a variety of sentences. We hope that you will now be able to make sentences using this word.
