The volcanic vein in Avlaki tis Petra is a characteristic landform created by the latest volcanic activity on Lesvos, which began 17 million years ago.
The vein at Avlaki was formed by intrusion of dacitic magma into pre-existing volcanic rocks that were created during the main phase of volcanic activity 18.5 to 17 million years ago. The penetration of the lava into the upper layers of the crust led to its cooling and solidification.The rocks that surrounded the volcanic vein were eroded after the end of the volcanic activity, while the dacite rock, more resistant to erosion, created the landform that crowns the hill in Avlaki.
What is a volcanic vein?
Volcanic veins are structures of volcanic rocks, oriented vertically or slightly inclined with respect to the rocks in which they are hosted. As a rule, they cut through pre-existing rocks.
How are they created?
Volcanic veins are created during periods of intense volcanic activity, when rising igneous material from the earth’s interior, following a large crack in the crust, penetrates older geological layers and rises to the surface. The erupted magma then cools and solidifies, taking the shape of the fissure.
What are their dimensions?
Although the thickness of the veins can be from a few centimeters to tens of meters, it usually ranges from 1 to 20 meters. The length of a vein is generally greater than its thickness and is controlled mainly by the discontinuities of the rocks in which it has been penetrated and trapped.