Which of the following are true with respect to the Indian Peninsular Plateau? 1. The southern plateau block is formed mainly of granites and gneiss 2. The Deccan lava plateau is an elevated tableland consisting of horizontally arranged lava sheets 3. The Malwa plateau dominates the Vindhyan scarps forming the northern flank of the plateau 4. The troughs of the Narmada and the Tapti are interposed between the Vindhyan and the Satpura ranges.