Guyana the dryer savannah areas in the south-west; and the smallest interior lowlands (interior savannah) consisting mostly of mountains that gradually rise to the Brazilian border. 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 water
American Falls can view the falls from the bank of the river, as well as on Goat Island and Luna Island, which are accessible by a pedestrian bridge that crosses the rapids of the Niagara River upstream from the falls. The falls are viewable head-on from the Canadian side in Niagara Falls, Ontario. The ledge of the American Falls is shaped in a modified "W" form, caused by numerous rock falls over the past 150 years which have resulted in the huge mound of rock at its base. The most notable recent rockfall occurred in 1954 with the collapse of Prospect Point