Some of Guyana's highest mountains are Mount Ayanganna (), Monte Caburaí () and Mount Roraima ( – the highest mountain in Guyana) on the Brazil-Guyana-Venezuela tripoint border, part of the Pakaraima range. Mount Roraima and Guyana's table-top mountains (tepuis) are said to have been the inspiration for Sir Arthur Conan Doyle's 1912 novel ''The Lost World''. There are also many volcanic escarpments and waterfalls, including Kaieteur Falls which is believed to be the largest single-drop waterfall in the world by volume. North of the Rupununi River lies the Rupununi savannah, south of which lie the Kanuku Mountains.