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Distinguish between Dyke and Sill or Discordant and Concordant bodies
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written 6.3 years ago by | modified 6.2 years ago by |
Dykes (Discordant type) | Sill (Concordant type) |
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Dykes are discordant igneous bodies of more or less tabular shape and exhibiting a cross -cutting relationship with the country rocks . | Sills are tabular concordant igneous bodies lying parallel to the structure of the country rocks . |
They occur commonly in the form of wall like masses of exactly or nearly vertical attitude | They are commonly sheet like masses , occurring within the country rocks and may be variable thickness |
Dykes are commonly formed due to development of cracks within country rocks and their subsequent filling up with the igneous intrusives | Their mode of occurrence parallel to the bedding planes of the sedimentary rocks forming the region is suggestive , to lay man , of their belonging to the sedimentary rocks series , in which they actually occur as intrusive bodies . |