Welded tuff is a pyroclastic rock, of any origin, that was sufficiently hot at the time of deposition to weld together.
22.
However, no tephras or pyroclastic rocks have been found at Hoodoo Mountain that were erupted the same time as these lava flows.
23.
Volcanic activity at Ice Peak during this period produced lava flows and pyroclastic rocks, which mixed with meltwater to produce debris flows.
24.
The geology of the undersea portion of the tunnel consists of volcanic rock, pyroclastic rock, and sedimentary rock of the Neogene Period.
25.
Its summit consists of pyroclastic rocks ( " Schwei�schlacken " ) that form a volcanic crater that is open towards the east.
26.
Here, it was found in a pyroclastic rock sequence, believed to be emplaced during the eruptive phases, when the caldera collapsed.
27.
Borates are formed when boron bearing solutions, caused from the leaching of pyroclastic rocks, flow into isolated basins where evaporation then takes place.
28.
Behind the dolerite, to the south, the vent is filled with pyroclastic rocks that break down more easily, mostly a coarse tuff agglomerate.
29.
Interbedded pyroclastic rocks vary from thin beds of fine tuff to thick units of breccia, and reveal some ongoing volcanic activity during the period of deposition.
30.
Most of the crystal fragments of farneseite collected so far are less than 3 mm in diameter, occurring in vugs between interlocking feldspars in pyroclastic rocks.
