Bursa: High above the northwestern Turkish city of Bursa, seven alpine lakes scattered across the summit of Uludag preserve traces of geological processes that unfolded over millions of years. Known as the Lakes Region, the area sits near the summit of Uludag, a mountain that rises to more than 2,500 meters (8,200 feet) and is one of Trkiye's best-known destinations for winter sports and nature.
According to Anadolu Agency, the seven lakes-Aynali, Karagol, Buzlu, Kilimli, Heybeli, Kovukdere, and Cayirlidere-were shaped by glaciers and are fed by surface and groundwater. Their rocky basins and surrounding formations offer a glimpse into the geological evolution of the mountain, while the lakes themselves have become destinations for hikers, mountaineers, and nature enthusiasts.
President of the Southern Marmara Branch of the Chamber of Geological Engineers, Mehmet Yildiz, emphasized that the lakes should be regarded as part of Trkiye's geological heritage. "These are natural formations that have the characteristics of geoheritage. They form over millions of years," Yildiz told Anadolu.
Yildiz noted that the lakes were not created over short periods of time or through artificial intervention but formed through geological processes lasting millions of years. He said the concept of geoheritage, natural formations that provide evidence of Earth's geological history, has yet to become fully established in Trkiye. He pointed to Mount Nemrut, Cappadocia, and Lake Salda as examples of sites in Trkiye recognized for their geological significance, adding that Uludag contains numerous formations that could also qualify.
Understanding such formations is important for studying how the Earth has evolved over time and guiding future geological research, Yildiz said, arguing that the lakes should be protected and given formal geoheritage status. The Chamber of Geological Engineers conducted fieldwork in the Lakes Region in 2023 together with members of the Association for the Protection of Geological Heritage, known as JEMIRKO, as part of efforts to secure geoheritage status for the area.
Despite its rugged landscape, Uludag is not a volcanic mountain, Yildiz explained. The mountain was formed through tectonic activity and magmatism, rather than volcanic eruptions. As a result, the lakes at its summit are not crater lakes. Instead, they were formed by glaciers that eroded the underlying geological formations. Moraine deposits-accumulations of rock and sediment left behind by glaciers-helped create natural basins where surface and groundwater could collect. The result is a series of lakes whose present-day appearance reflects a much longer geological history.
Water levels in the lakes have risen this year compared with recent years, the expert said, attributing the increase to heavy snowfall over the winter and spring rainfall. Snow acts as a natural water-storage system, gradually feeding the mountain's groundwater and springs as it melts, he said. "Even in this season, when you go up, you can still see masses of snow that have not melted," Yildiz said, adding that the continued supply of meltwater and rainfall has increased water levels across the area.
He said visitors can see considerably more water in the lakes this year than in the previous five years, although their depths vary depending on the geological structure of each basin. Kilimli Lake, for example, has a depth of about 4.5 meters, while the walls surrounding another lake rise to about 300 meters, according to Yildiz.
For visitors, the seven lakes offer more than a scenic destination. For geologists, they are part of a natural record stretching back millions of years-one that researchers say should be protected before more of its history is lost.