Great masses of granite, syenite and diorite were intruded at this period, and send tongues even into the andesitic tuffs.
The well-known volcanoes, Montagne Pelee, the Soufriere of St Vincent, Krakatoa, Tarawera and Bandaisan have within recent years emitted great quantities of andesitic rocks with disastrous violence.
The Cretaceous beds lie in a broad synclinal upon the eastern flank, but the greater part of the chain is formed of Jurassic beds, through which, on the western margin, rise the numerous andesitic volcanic centres.
They are agates derived from the andesitic lavas of Old Red Sandstone age, chiefly in the Ochils and the Sidlaws.
Higher up in the Cordillera there appeared to be a line of andesitic rocks; and beyond them, a fourth escarpment of the porphyritic conglomerate, again dipping eastwards or inwards.
The strata are inclined, as before stated, from 20 to 30 degrees eastward, towards an irregular north and south chain of andesitic porphyry and of porphyritic greenstone, where they are abruptly cut off.
Where the mica and quartz are abundant, the rock cannot be distinguished from granite; and it may be called andesitic granite.
In the region extending northward from Lake Tahoe to Sierra Valley enormous andesitic eruptions took place, and the products of these volcanoes are now piled up as high mountains, among which Mount Pluto nearly attains 9000 feet.
At the north of Lake Tahoe, "southwest of Reno, a large andesitic volcano poured forth lavas which extend between the Truckee River Canyon and the Washoe Valley.
They mark a period of active eruption on the part of some neighbouring acid andesitic vent in this neighbourhood, which the subsequent explorer may be able to identify with some volcanic “neck.
Masses of agglomerate of the same andesitic rocks lie about in places on the lower slopes, the included blocks, which are a few inches across, being sometimes rounded.
It is, however, evidently composed of basic andesitic rocks, occasionally amygdaloidal.
It contains pebbles and blocks of acid and basic andesitic rocks, and may be described as an altered hornblende-andesite tuff.
It is an area of basic agglomerates and basic tuffs and lies in the hollow between the basaltic mountain of Seatura and the acid andesitic hilly region of Ndrandramea.
That the porphyritic basalt represents a later flow around this old andesitic mountain is indicated amongst other things by this absence of tuffs and agglomerates.
The great alteration of the acid andesitic rocks exposed as the bed-rocks in this region may in all probability be attributed to the vicinity of these basaltic rocks.
It displays a characteristic andesitic groundmass, showing crowded felspar-lathes in flow-arrangement with average length of ·17 mm.
He describes in the case of Mango and other islands the manner in which cliffs of limestone form inliers in flows of andesitic lava.
Above the basic tuffs lie a series of tuffs, about 5 feet in thickness, and composed mainly of the debris of acid andesitic rocks of the hornblende-andesite type, such as occur in the Ndrandramea district.
In the frequent alteration of its andesitic rocks, and in the occasional occurrence of porphyrites, we have sufficient indication of the antiquity of this part of the island as far as its volcanic history is concerned.
The other materials of these deposits are derived from the degradation of basic andesitic rocks, and include also a little palagonite.
I did not ascend it, but found at its base a rock of the same andesitic type, differing from that of Ndrandramea in the more crystalline character of the groundmass, and having a specific gravity of 2·61.
After the cessation of the andesitic eruptions, a quiescent period of great length ensued.
The outpourings at first consisted of andesitic lavas.
It is composed of andesitic lavas of the augite type, is pierced by many fumaroles, and has a crater in the solfatara stage.
Amongst them I may mention those of Bougainville Strait, which are composed of andesitic lavas of the hornblende type.
While the Picture Gorge Basalt was flooding most of the John Day basin, several volcanoes in the vicinity of Strawberry Mountain erupted andesitic to rhyolitic lava and ash, and built up cones similar to Mt.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "andesitic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
