Orissa's ancient temple stones, some of which date to millions-of-years-old Gondwanaland, are vulnerable to erosion and decay, warns a report. Gondwanaland, regarded as the mother of all continents, was an ancient landmass that is believed to have fragmented and drifted into the present-day continents millions of years ago. Temples of Bhubaneswar, built between the seventh and 11th century, are constructed out of blocks of sandstones of Gondwana age. Three types of these ancient sandstones - red, yellow and white - are extremely vulnerable to erosion, says a recent report by scientists from the department of chemistry at B.J.B. College in Bhubaneswar in the journal Current Science.