or more in thickness; (2) Puys, where the ejections were often confined to the discharge of a small amount of fragmentary materials from a single independent vent."
The two leading types of volcanic areas are the plateaus, in which sheets of porphyrites, basalts and even trachytes were emitted, sometimes with wide discharge of volcanic ashes, and the puys, or isolated vents, or scattered groups of vents, which discharged comparatively a small amount of lava and ashes.
The Campsie, Kilpatrick and Dumbarton hills, the high ground from Greenock to Ardrossan, and the Carleton Hills in East Lothian are examples of the plateaus, while Arthur's Seat in Edinburgh and the Binn of Burntisland illustrate the puys.
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