Are "monoliths" giant, isolated rocks sitting in dirt, or are they continuous with bedrock
the trick is not all isolated rocks are produced the same ways. Of the two in your pictures  the first is an old volcanic events; intrusions, dikes, ect. depending on which rock in the region you are talking about. The whole deccan plateau region is full of them, some have been exposed on the surface via erosion. Basically everything else eroded faster than they did leaving them sticking out. 


The second was produced by the same effect (eroding slower than the rock around it) but this time it was just a hard massive sandstone formation surrounded by more easily eroded rock. It is part of the bedrock.