Trappean

Dark trappean rocks full of hornblende have in many places burst through these schists, and appear in nodules on the surface. ❋ Unknown (2004)

In fact, the great plutonic action is confined to the central portion of the island; there, rocks of the trappean and volcanic class, including trachyte, basalt, and tuffs and agglomerates associated with streams of lava, have made this a land of supernatural horrors. ❋ Unknown (2003)

By what train of investigations were geologists induced at length to reject these views, and to assent to the igneous origin of the trappean formations? ❋ Various (N/A)

The lodes are not ribboned, but consist of quartz, jointed across from side to side, exactly like trappean dykes. ❋ Thomas Belt (1855)

These, however, were sufficient to show me that the gneiss of Depilto was overlain conformably by the contorted schists; that the latter were followed by soft trappean beds, and these by thick beds of quartz-conglomerate, apparently derived from the degradation of the schistose rocks, with their numerous quartz veins. ❋ Thomas Belt (1855)

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 trachytes or trappean porphyries. ❋ Unknown (1851)

Fragments of granite have been observed at Teneriffe; the island of Gomora, from the details furnished me by M. Broussonnet, contains a nucleus of micaceous schist: — the quartz disseminated in the sand, which we found on the shore of Graciosa, is a different substance from the lavas and the trappean porphyries so intimately connected with volcanic productions. ❋ Unknown (1851)

Spain, and New Andalusia; and finally, the trappean porphyries of the provinces of Quito and Popayan. ❋ Unknown (1851)

This regular disposition of lithoid basaltic lava and feldsparry vitreous lava is analogous to the phenomena of all trappean mountains; it reminds us of those phonolites lying in very ancient basalts, those close mixtures of augite and feldspar which cover the hills of wacke or porous amygdaloids: but why are the porphyritic or feldsparry lavas of the Peak found only on the summit of the volcano? ❋ Unknown (1851)

Are these strata, contained in the trappean mountains, owing to muddy irruptions, or must we consider them as sediments of water, which alternate with volcanic deposits? ❋ Unknown (1851)

To this very ambiguous formation belong the trappean porphyries of Chimborazo and of Riobamba in America, of the ❋ Unknown (1851)

As the coasts of Portugal consist of basalts covering calcareous rocks containing shells, I imagined that a trappean formation, like that of the ❋ Unknown (1851)

This peculiar form, and the symmetrical arrangement of a few cones which surround the Brigantine, made me at first think that this group, which is wholly calcareous, contained rocks of basaltic or trappean formation. ❋ Unknown (1851)

It may almost be admitted as a general rule that whenever the mass of mountains rises in that region of the tropics much above the limit of perpetual snow (2300 to 2470 toises), the rocks commonly called primitive (for instance, gneiss-granite or mica-slate) disappear, and the summits are of trachyte or trappean-porphyry. ❋ Unknown (1851)

Mexico, have taken place in countries covered with trappean porphyry, ancient basalt, and volcanic ashes, so the peak of Teyde has raised itself amidst the wrecks of submarine volcanoes. ❋ Unknown (1851)

Arso in the island of Ischia, whiten at the edge of the crater from the effect of the acid vapours; but internally they are not found to be colourless like that of the feldsparry lavas of the Solfatara at Naples, which perfectly resemble the trappean porphyries at the foot of ❋ Unknown (1851)

Sometimes both varieties meet in the same fragment, as we observed also in the trappean porphyries of the valley of Mexico. ❋ Unknown (1851)

Teneriffe primitive strata, or even those trappean and ambiguous porphyries, which constitute the bases of Etna, and of several volcanoes of the Andes, we must not conclude from this isolated fact, that the whole archipelago of the Canaries is the production of submarine fires. ❋ Unknown (1851)