roof rock meaning in Hindi

These volcanics created the " roof rocks " into which were emplaced the mafic formations of the Duluth Complex.
Hydraulic fracturing has been applied to preconditioning strong roof rock over coal longwall panels, and to inducing caving in both coal and hard rock mines.
Specific exploratory geological drillings were carried out between 1979 and 1999, and from the early eighties the results showed that the Gorleben salt dome could actually be unsuitable because of its unstable roof rock and contact with the groundwater.
If this downward protruding mass of roof rock still has a connection to the main, surrounding mass of country rock, they are known by structural geologists as either " septa " or " screens ."