Roopak:
Do you mean the elevation or the perching height of the frog? The elevation would be somewhere between 1650-1700 m. The perch was a rock about 1 m high, surrounded by equally tall grass clumps. (Had to walk into the the said grass to reach the frog).
Not sure about the rock. It is not the laterite that makse up the coastal plateaux. We noticed a difference in the type of rock as we ascended, some of the rock near the peak was of the silvery-white kind that one sees generally in the Himalayas. Again, I'm no expert, it may not actually be what it seemed like.