A large number of dikes of igneous rock occur in the Atlantic coast region from Prince Edward Island southward to Alabama and Georgia, and vast lava-flows of ancient date are still preserved about the south shore of Lake Superior.
In the case of several of these mines, igneous rock is near at hand, and the ores are believed to owe their concentration largely to the action of heated waters.
This is also another form of igneous rock, admitting of every variety of composition.
An igneous rock composed of orthoclase, elæolite, and sodalite.
A dark-colored, basic, igneous rock, composed essentially of pyroxene and a triclinic feldspar with magnetic iron.
Favorable conditions for trapping the oil may be furnished by impervious clay "gouges" along fault planes, or by dikes of igneous rock.
The magnetite crystals of these deposits interpenetrate with the other constituents of an igneous rock, commonly of a gabbro type, and the deposits themselves are essentially igneous rocks.
An igneous rock composed of orthoclase, el\'91olite, and sodalite.
Where the highlands are of igneous rock, such as granite, and mechanical disintegration is going on more rapidly than chemical decay, these conditions are recorded in the nature of the deposits laid offshore.
The nucleus of igneous rock is four miles in diameter and more than a mile in depth.
Defn: An igneous rock of semiglassy nature, having a luster like pitch.
Defn: An igneous rock,usually light gray in color and breaking with a rough surface.
Defn: A column of igneous rock formed by congelation of lava in the conduit of a volcano and later exposed by the removal of surrounding rocks.
All the isolated hills in the basin of the Forth are formed of knobs, bosses, and sheets of various kinds of igneous rock, which are more durable than the sandstones, shales, and other sedimentary strata by which they are surrounded.
The hills that occur within this inner region of the Central Lowlands are usually more or less isolated, and are invariably formed by outcrops of igneous rock.
In hand specimens and boulders, and even on a near view of the hills, this rock appeared quite an igneous rock, but when an extensive section was exposed, it could be seen to be distinctly stratified.
The geological structure of this rocky ravine was very intricate, from the great mass of igneous rock, granite, greenstone, and amygdaloid, which everywhere occurred.
I did not see any eruption of igneous rock on any part of the day's journey.
Almost invariably the ores are directly associated with limestone and an igneous rock (granite), both of late Paleozoic Age.
The greatest mines in the world are in South Africa, where the diamonds occur in masses of rather soft (decomposed) igneous rock, evidently having crystallized during the cooling of the molten masses.
A Ledge of Igneous Rock (Granite) in Northern New York.
The Spanish Peaks of southeastern Colorado were formed by the upthrust of immense masses of igneous rock, bulging and breaking the overlying strata.
The source of the intrusive sheet may often be traced to some dike (known therefore as the feeding dike), or to some mass of igneous rock.
No igneous rock type is known which could be formed by the fusion of any of the carbonate rocks such as limestone or dolomite, or of the more siliceous rocks, such as sandstone or quartzite.
It is a convenient name for use in the field when doubt occurs as to the real nature of an igneous rock.
The above list will hopefully provide you with a few useful examples demonstrating the appropriate usage of "igneous rock" in a variety of sentences. We hope that you will now be able to make sentences using this group of words.
