![]() On such occasions, the products are usually crossbedded breccias that have a foreset dip of approximately 25 degrees. Pyroclastics may also form when a lava flows into the sea, or even a lake. Large amounts of ash from the country rock are associated with eruption when this happens. This may occur when the rising magma comes into contact with ground water. Pyroclastics form by the expansion of gas contained in the parent magma. Acid magmas are more viscous, hence they are reluctant to release gas and this results in high explosiveness. Characteristically there are more pyroclastics associated with acid magmas than basic. Pyroclastic rocks are the products of volcanic explosions that is, they are fragmental pieces of rock, whether they be minerals, crystals or glass, ejected from the vent. © Copyright, 2001 by R.A.Kanen, All Rights Reserved
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