Freshwater Lake Ulubat (c. 1.5

Surface water and sediments derived from the southern Marmara region (= Susurluk Drainage basin-SDB) transport to lakes Manyas and Ulubat first and then go to the Sea of Marmara via the Kocasu River only. The present drainage system of the SDB provides a good opportunity to study erosion rate and subsequently occurrence times of large-scale valleys in the region. To achieve it, depositional characteristics and ion contents of the ancient lacustrine sediment have been investigated and re-interpreted using cores taken from Lake Ulubat. The boron content of these sediments increased upward suddenly at 4 m depth, most probably due to starting of erosion at Emet borate beds in the drainage basin. Taking into consideration equilibrium between natural erosion and sedimentation, the incision rate in the Emet valley was found to be 1.4 cm.yr-1. From here one can calculate a time span of 75 kyr for the formation of the whole valley itself. However, it is known that working of the geological processes was not monotonous in the past; hence, this date is not absolute. Newertheless, formation of the large valleys of the southern Marmara region should not be older than 300 kyr. An important reason rapid erosion was likely lowered base-level as the Marmara Sea was a closed lake during the last Glacial Period. High altitudinal difference between source and depositional areas caused acceleration of for erosion.

Freshwater Lake Ulubat (z mean = 1.5-2.0 m and Area = ~138 km 2), NW Anatolia, Turkey was filled in by fine-to-medium-grain silts during the late Holocene. Deposition in Lake Ulubat has been 1.6 cm yr-1 for the last 50 years, but the sedimentation rate over the last ~1,600 years was lower (0.37 mm yr-1). The organic matter and carbonate contents of the infill show cyclic changes that reflect environmental fluctuations. The silt-dominated lithology and the vertically uniform heavy metal distributions are probably due to wind-controlled sedimentation in the lake. Heterogeneous mud, derived from a large, mountainous drainage basin, is deposited in the lake mostly during summer, June to October, when conditions are hot and calm. Winter months are stormier and sediments are re-suspended due to the shallow water depth and the effect of waves on the lake bottom. It is likely that re-suspended sediments, particularly fine-grained particles, together with the heavy metals, are transported out of the lake via the outlet, especially during periods of high lake level. This resuspension and removal process probably caused the lake sediments to become silt-dominated and depleted in heavy metals. The role of broad shallow lakes in sequestering sediments and heavy metals can be described more accurately when wind data are considered. Such information may also be helpful for land-use planning in downstream areas.

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The study area covers an area of approximately 600km 2 in the Gerede district of the Province of Bolu, which is located in 1/25.000 scale G28 a1 a2 a3 a4 topographical sheets showing northwest of Turkey. This study tried to reveal the general geology of the study region, which is bound by the Mengen district on the north and Gerede district on the southeast. The study area includes various rocks with similar lithology and stratigraphic sequence with ages ranging from the Paleozoic to Quaternary period. Although the base complex, which constitutes the oldest, rocks of the region, cannot be observed in the mapped geographical area in Gerede, though it's known to exist at the base. The limestones developed on the tithonic facies of Late Jurassic-Early Cretaceous age on the base complex of Permo-Triassic period are incompatible. It is determined that the Upper Jurassic-Lower Cretaceous aged limestones are rich in titonic facies and rich in calpionel contents. As a result of detailed paleontological and biostratigraphic studies on the samples; 3