On a scale less than 3 mm, this photo of a metamorphic rock called Schist gives the idea of the intense deformation that rocks undergo during the collision of continents that accompanies the build-up of a mountain chain like the Alps. Not only earthquakes take place where plates collide, but also plastic deformation, and folding and stretching of solid rocks, which at depth may behave like silly putty. On the right, thin layers of colorful mica and black graphite have been intensely and tightly folded (“crenulated”). On the left, the blue geometric patch is a crystal of garnet, around which the soft mica-graphite matrix has wrapped. This specimen comes from the Pfitsch-Vizze Valley in South Tyrol, Italy Width of view 2,7 mm.
|Photo Location:||Microscope Laboratory, Padua, Italy (rock comes from Bozen, Italy), Italy|
|Copyright:||© Bernardo Cesare|