NM4267 : Chilled Margin

taken 4 years ago, near to Portuairk, Highland, Great Britain

Chilled Margin
Chilled Margin
When hot molten rock comes up against colder material, it cools faster than it otherwise might, and the result is a margin of very fine-grained crystals. In this example you cane easily see the wavy line of tiny dark crystals along the meeting of the dark quartz-dolerite and the pale microgranite. The interesting detail about this particular example is that both magmas were still hot when they came in contact, and 'chilled' is a relative term - the quartz-dolerite might have been 800 to 1000 degrees Celsius, and the microgranite a mere 500 or 600 degrees, but the difference of a few hundred degrees was enough to produce a 'chilled' margin!
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NM4267, 22 images   (more nearby )
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Date Taken
Saturday, 14 September, 2013   (more nearby)
Tuesday, 17 September, 2013
Geographical Context
Geological interest 
Subject Location
OSGB36: geotagged! NM 4258 6757 [10m precision]
WGS84: 56:43.7126N 6:12.5958W
Camera Location
OSGB36: geotagged! NM 4258 6757
View Direction
NORTH (about 0 degrees)
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