File:Tsingy de Bemaraha National Park, Madagascar.jpg

English: This true-colour image shows a portion of Madagascar’s Tsingy de Bemaraha National Park. Although less dramatic from the sky than from the ground, the rock formations are still visible in this image, especially near the top centre. Together, naked rocks and vegetation produce a patchwork of green and grey. The outcrops appear to form long lines that run roughly north to south, but this is due partly to the angle of sunlight. Just as the clouds cast their shadows to the west, the rocks cast their longest shadows in that direction, too. In reality, breaks along multiple directions dissect the spires of rock, forming a cross-hatch pattern. The formation of these unusual rocks actually began some 200 million years ago when layers of calcite accumulated at the bottom of a Jurassic lagoon, forming a thick limestone bed. Later tectonic activity elevated the limestone, and as sea level fell during the Pleistocene ice ages, even more of the limestone was exposed. No longer underwater, the ancient sediments were carved by monsoon rains, which washed softer rocks away and left tougher rocks standing. Meanwhile, groundwater carved caves below the surface. As cave ceilings gave way, canyons formed between rocky towers. Today, the limestone formation shows a combination of jagged spires and rounded surfaces.