Caves of varying sizes and shapes are scattered among the rocks towering along the valley fed by the Fındıcak and Çınarlı streams. These natural structures belong to the Chalcolithic era (Copper Age), and some of them have been carved to extend the interior. A 1941 excavation in the area, headed by Ankara University Professor Tahsin Özgüç led to the discovery of several prehistoric shelters and yielded many prehistoric artifacts including axes, cutting tools, knives, bracelets and even needles exemplifying advanced craftsmanship. A large piece of rock overlooking the intersection between the Çınarcık and Fındıcak valleys is known by the name 'Delikli Kaya', meaning "perforated rock". Delikli Kaya features a series of man-made steps, which have been traced back to the Phrygians.