Sills refers to the concordant igneous bodies that are formed when hot magma intrudes and gets trapped between the relatively older sedimentary rock layers. This are oriented parallel to the ground surface.
D(i)kes refers to the discordant igneous bodies that are formed when the hot intruding magma rises up vertically towards the surface.
Both these structures ranges in thickness from about a few millimeter to a few meters.
The area of land<span> that is drained by a particular </span>river<span> and its tributaries is </span>called <span>either a </span>river<span> basin or </span>drainage<span> basin. </span>
The biologist is the person who would be interested in determining the existence of any pattern or characteristics with in a species and relate it to the characteristics possessed earlier by the species.
