Vural Yavuz

Synchronous Last Glacial Maximum across the Anatolian peninsula

Abstract Uludağ is a prominent mountain in northwestern Turkey where glacial deposits have been documented in the Kovuk Valley and the glacial history has been reconstructed based on 31 cosmogenic 10Be exposure ages from glacially transported boulders and bedrock. The results suggest that the Kovuk Glacier began advancing before 26.5±1.6 ka. It reached its maximum extent at 20.3±1.3 ka, followed by a re-advance at 19.3±1.2 ka, both during the global Last Glacial Maximum (LGM) within Marine Isotope Stage 2. The timing of the LGM glaciations in the Kovuk Valley is consistent with the investigated LGM glaciations in other mountains of Anatolia, the Mediterranean and the Alps. Based on the geomorphological ice margin reconstruction and using the accumulation/ablation area ratio (AAR) approach, the equilibrium line altitude (ELA) of the Kovuk LGM glacier was c. 2000 m above sea level for an estimated AAR of 0.67. This indicates a c. 1000 m lowering of the ELA for the LGM compared with the modern ELA estimate. These lines of evidence are consistent with the LGM glaciers that have been documented elsewhere in the Anatolian Mountains. Supplementary material: An input file for exposure age calculation in the CRONUS-Earth online calculator and an KML file for sample locations are available at http://www.geolsoc.org.uk/SUP18878

The Frozen Bosphorus and its Paleoclimatic implications based on a summary of the historical data

Historically, the first evidence of a frozen Bosphorus was noted during the time of Herodotus. Analysis of the historical data about freezing events in the Bosphorus (at Istanbul) reveals the existence of four main cold periods since 1 AD. The first occurred around the 1st cen tury. Although the temperature was close to, or perhaps a little lower than, that of the present, three succes- sive freezing events are indicated between 7-17 AD. The second cold period was in the 4th century, when another freezing event was reported in 401 AD. After a slight temperature increase up to the beginning of the 8th century, the third cold period extended from the mid-8th to the 13th century, during which the Bosphorus and even parts of the Black Sea were repeatedly frozen, and floating ice masses entered the Sea of Marmara. Winters were markedly mild for 400 years starting from the mid-13th century. The fourth cold period began early in the mid-17th century and has lasted to the present day; it has been characterized by severe winters, however, the intensity of the winter cold has gradually diminished during this interval. Our aim is to evaluate existing historical data on these modern cold periods, to analyze instrumental meteoro- logical data, and to provide suitable data for future correlations with the amplitude and frequency of paleoglacier advances both in the Alps and in Anatolia. These four periods are more or less coeval with the phases of glacial advance in the Northern Hemisphere. As the accuracy of the historical data increases with time, evidence is more detailed for the fourth period. During this interlude, which coincides with the Little Ice Age, freezing events were not all coeval with reliable central European evidence. This can be explained by the low index of the North Atlantic Oscillation that resulted in higher precipitation ratios.