coursera.org/amnhearth-002/forum/thread?thread_id=9 The rock piece which I chose came from The Major Arc Bergen Complex which encompasses both the Ulriken and the Rundemanen Mountain , and after a careful study of the various resources I have concluded that ,the rock was originally a igneous rock but changed to a metamorphic rock during the Caledonian Orogeny.

Caledonian Orogeny :- It was a mountain building era which was caused in the Scandanavia and the other surrounding areas like the British Islands , Scotland and the around areas lying within the same latitude , which took place around 490-390 million years ago .

The Major Bergen Arc is a very broad term to say as it covers a huge area , but the place from where the sample was taken comes under Ulriken Gneiss Complex which forms the Rundemanen Formation .At present the entire area is made up of a huge Gneiss mass and has different minerals in it which include Garnet , Mica , Metagabbro and Granite .Not only has it gone undergone the deformation of the Caledonian metamorphoism but also the Precambrian deformations (541.0 1.0 Ma).

Ma - refers to million years ago .

Formation of the original feature :-After seeing the various folds and the cut lines in the rocks were originally formed in the Precambrian period(541.0 1.0 Ma) .This can be clearly seen in the lower layer of the rock sample as the lower layer shows the preserved rocks . That layer is also a layer of Gneiss but has been divided under the category of Biskopshavn Minigmatic Gneiss . This contains the rocks in lower layers , which have remained relatively undisturbed and are called as the migmatic rocks having a foliated structure . 1. Migmatic rocks : - . A rock which is a mixture of metamorphic and a igneous rock and is formed when the metamorphic rock partially melts and then recrystallizes to form an igneous rock . (The different colour band we see in the rock which looks like a sedimentary rock are actually because of the combination of the metamorphism and the recrystallization.)The shifts , veins and the other cut lines that we see are because of the shear zones and Pegmatite a mineral also found in these rocks have coincided with it to cut it at sharp angles . 2.Mineralogy :- a )The lowest layer has a foliated structure i.e. that it has been formed in the layers . b) The other layers have a coarse grained structure and have specks of Mica in between which gives it a shiny appearance .

Reason for the present day state :-The original rocks were igneous rocks and which had been metamorphoised and different rock samples show different characteristics . a) The rock sample was formed due to very high temperature difference during the Caledonic Deformation but this difference was not present in the precambrian deformation hence this structure . b) So the theory of partial melting and great temperature difference ( Hydrothermal Pressure) both are applicable. c) Links for the Information :-http://folk.uib.no/nglhe/BergenGeo.htmlhttp://www.academia.edu/3437681/Geology_of_the_Minor_Bergen_Arc_West_Norwayhttp://folk.uib.no/nglhe/Papers/JSG%201987%20Holst%20Fossen%20Strain%20around%20fold.pdfhttp://folk.uib.no/nglhe/Papers/NGU%201988%20Rundemanen.pdfhttp://books.google.no/books?id=rMVNE0F2SckC&pg=PA13&lpg=PA13&dq=making+of+land+geology+of+norway&so...http://en.wikipedia.org/wiki/Caledonian_orogenyhttp://books.google.no/books?id=EQhfhUhjQJAC&pg=PA191&lpg=PA191&dq=geology++of++rundemanen&source=bl...