International Symposium on Geography Environment and Culture in the Mediterranean Region

GEOMORPHOLOGY OF THE UPPER PART OF KOCAÇAY RIVER BASIN, (İVR İND İ-BALIKES İR, NW )

Kamile GÜLÜM 1

Abstract Study area: the upper watershed of Kocaçay river-basin is located on the south of the . It covers an area of 751 km². Policyclic topografic forms are dominant since different tectonic and climatic process have affected the study area. The land forms of the study area are closely related to the lithological properties. Dominant topographic shapes are plateaus as they are dissected by running water. Although the dominating topographical features today show a mature type of topography, valleys are generally younger. Drainage systems have mostly been formed during the Pliocene Age . It has been developed in the Quaternary. In fact, the valley system is of the Plio-Quaternary period. The topographical discordance found in the study area is probably the result of Post-Alpine tectonical uplift that occurred at the end of the Pliocene Age and the beginning of the Quaternary. There are three erosional surfaces at an elevation of 550-750 meters, 300-520 meters, and 210-300 meters. These surfaces indicate different erosional and depositional process to have occured in the study area. In other words, tectonic movements are responsible for the formation of erosional and depositional surface. Erosional activities continue in the river valley since the base level is lowered or backward. As a result, the erosion process continues. Valleys are still in the character of young valleys. In fact, when the topography in the upper track of Kocaçay river basin is considered as a whole, one can say that the development is still in the young stage. Key words: Gemorphology, Kocaçay, superimpose valley

Introduction The Upper part of the Kocaçay Rivershed, which is handled as the research area, is located in the Southern Marmara Region in the northwest of . The research area neighbours with the Manyas Plain in the north, Balıkesir Plain in the east, Sava ştepe Plateau in the southeast, Madra Mount in the southwest, Edremit Plain in the west, and Şap Mount in the northwest. The area, which is blocked by the mountains in the northwest and southwest, extends towards the southeast and southwest. The Madra River (Kocaçay), which is formed through the plains on the base of the valley and plateaus with the altitude of 300-850 m, is the dominant element of the research area. The highest point in this area is Maya Hill(1344 m) on Madra Mountain and the lowest point of this area is İvrindi Plain (200 m). In the fields where the South Marmara climate is dominant, the vegetation is made of the poor forests constituted of the bushes and cluster pines and oak trees in the low altitudes. In contrast, in the high altitudes where the humidity increases with the altitude on Madra Mountain and Şapda ğ, there are robust forests consisting of black pine trees and chestnut formations. The vegetation has been destroyed over the years in a large extent. The forests exist in the south-southeast and north-northwest areas. There are various kinds of soil in the research area. In general, the dominant soil is zonal soil. But there are also azonal soils made on the alluvial and colluvial deposits. The

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kinds of soil that dominantly exist in the area are red soils, brown soils, and Mediterranean soils. These soils lack lime and calcium as do the forest brown soils. The population is dense in on the plains. On the contrary, the population is scarce in the sloping ares in the south and and the areas covered with forests in the southwest and northwest.

Figure 1: Location map of study area

Some problems emerging from the physical, human living, and economical features of the research area cause applied geomorphologic problems. While the sloping, destruction of vegetation, and climate features (heavy rains, etc.) cause erosion around the plains, the rivers in the plains with less sloping overflow. Because these fields are alluvial fields which are rich in underground waters they increase the earthquake intensity. In the fields where the valleys are common and the sloping values are high, there have been eroded fields through lithologic characters.

Geology Paleozoik terrain, which is composed of mainly limestone, covers most of the mountainous areas leading in the southern part of the area. Mesozoic terrain is associated with sedimentary rocks such as conglomera and sandstone and Kozak granitic pluton. Terrary: clayev limestone, sand stone and volcanic tuffs, andesites form terriary formation. Quaterner is prepresented with the alluvial materials.

Geologic Evaluation of the Area The western part of the Anatolia was exposed to an extensional regime during the neotectonic period. In that period, some part of the study area was uplifted and depressed along some of the fault lines so the tectonic basin was formed in which detritic material accumulated. The study area is located between the Kaz Mountain and the low-land southern part of the Marmara Region. During the Mediterranne Period the vertical tectonic movements led to the hors-graben system. Namely, the gulf of Edremit and the low land of Marmara region fits International Symposium on Geography Environment and Culture in the Mediterranean Region

to grabens and Kaz Mountain is the main horst area which abruptly rises in the northern part of the Edremit Gulf. During the Miocene Period, the study area covering the eastern part of the Kaz Mountain was exposed to erosion due to lake levels occupying the lowland areas and as a result neogene erosional surfaces developed. At the end of the Neogene Period, the study area again uplifted. Consequently, the river set up on the neogene erosional surfaces cut its own valley. In other words, the uplifting of the area has caused the rejumation of fluvial erosion. As a result, dissected erosional surfaces have been converted into plateaus in appearence. Geomorphological Units The research area which has the characteristics of a plateau is composed of strong rocks and a bit higher than the level of plateaus are categorized under the name of “ High Lands and Mountains.” Apart from the high lands and mountains, it is also possible to divide and classify the plateaus which take the widest part of the research area in terms of the characteristic features and different structures and lithologic elements. It is even possible to divide them into smaller categories classifying them under the name of “ Flat and Rough Plateau Surfaces.” On the contrary, all the plains and alluvial base flat places that have come into being as a result of the cavity in plateau have not been taken into the “ Flat and Rough Plateau Surfces” because of the collectivity of the morphological unit. They have been classified and explained under the headline of “ Plains and Base Flats.” Although the upper line of the Kocaçay Valley seems to have a rough and high topography, it is characterized with the plateaus which take up a large field in the research area and a flattened and monotonous topography. However, in general, the area draws attention with diversity of the geomorphologic forms that it includes.

Figure 2: A picture of Madra Valley International Symposium on Geography Environment and Culture in the Mediterranean Region

Figure 3: Geologic map of the study area

Figure 4: Geomorphologic units of the study area

International Symposium on Geography Environment and Culture in the Mediterranean Region

Hiıgh Lands and Mountains This part in the southwest of the research area includes Madra, Kozgeçit, Çetin, Mısırtarlası and Haydar streams and the watershed. They are the highest points of the Madra Mountains. It reaches 1343 m in Maya Hill. There is a high land in İkizce, Kılcılar, and Büyükyenice villages where the altitudes of the Madra Mountains decrease, which is called Asar Tepe (816 m). The highest point is Mount Sabla whose altitudes decrease from Madra Mountain which is 1110 m high. Göldede Hill (871 m),which is located on an old volcanic cone on the northeast part of the mountainous land, stretches through Madra Stream (Kocaçay) and Yahu Stream. Havran Stream flows into the Aegean Sea and the Kocaçay flows into the Marmara Sea by means of Manyas Lake and Stream. Mount Madra combines with Mount Sap which is a part of the Kaz Mountains Range by means of a bridge of 550 m length from the north. This bridge which includes the highway between Balıkesir and Edremit separates the Aegean Basin and Marmara Basin. Göktepe (937 m) is an important rough place that is a range of Şap Mountain towards the east.

Plateaus Gümeli Plateau The Gümeli plateau, which is in the south-west of the research area, is situated between Mount Madra in the south and the İvrindi Plateau in the north. The Gümeli Plateau covers a minor place in comparison with the İvrindi Plateau. However, its average altitude level is higher than that of the İvrindi Plateau. In terms of the crack of the surface, Gümeli Plateau has a considerable value over the other. It makes a high and dominant relief in the north parts of Mount Madra from which the Kocaçay River originates. The Gümeli Plateau is blocked from the east by the Kurucu Mountain range. Faults, which have a considerable effect on the formation, also have a great role in shaping the topographic characters of the Gümeli Plateau. İvrindi Plateau The İvrindi Plateau is the second biggest plateau that lies between the “Main Geomorphologic Units” in the research area. The southern part of the plateau is blocked by the Kurucu mountains and Kocaçay Valley. İvrindi, Korucu, and Kayapa, which are the biggest allocation units in the research area, are in this plateau. The northwest area of the plateau constitutes a big part of the research area. The Gokçeyazı plain and Ali Demirci plains are located in this area where the altitude levels are between 250-350m. The Kocaçay Valley loses the characteristics of a valley in the north northeast of the area. The Kocabük gorges in the northeast part of the area is a valley that has been formed by Kocaçay in lime stone belonging to Üst Permien. The most important characteristic feature of the Kocabük gorges is that it has a meander. Kocaav şar gorges: Kocaçay forms two meanders in the valley which widen in the north part of the Kocaav şar gorges and continues into the valley named Kocaav şar. Plains and Flat Bases Flat bases and plains, which constitute the main geomorphologic units, cover 80% of the research area. High fields and mountains constitute a part which is a little smaller than 20% of the research area. The names of the plains and flat bases are as follows: Madra S. Flat Base, Haydar, Yahu , ( between Büyük Ilıca and Karaçepi ş Villages), Kobaklar, Arpacık , Ta şotluk, Kantar, Salkım Dadalar streams Flat Bases, İvrindi Plain, Gökçeyazı Plain, Kocaav şar Flat Base, and the Alidemirci Plain.

International Symposium on Geography Environment and Culture in the Mediterranean Region

Figure 6: A picture of the Ivrindi Plain

Geomorphologic Evoluation The neogene basin in the upper part of the Kocaçay River was formed by the vertical tectonic movements in the Oligocene-Miyogene period. The plateau surfaces in the surroundings of the Ivrindi and Gökçeyazı plain were uplifted. During the Lower Tertiary Period, notably lower Miocene, the volcanic eruption began. The pre-neogene terrains are found in the Gümeli and Ivrindi Plateaus covered by the volcanic material composed of andesits, dasits, and tuffs. The basins, which were formed in the Oligo-Miogene, were mostly occupied by Neogen Lake in which volcanic and sedimentary material was accumulated by fluvial processes. Fluvial depositional processes continued at the end of the Lower Pliocene. As a consequence, erosional and depositional processes led to the formation of erosional surfaces in the south, west, and eastern part of the area. Second erosional surfaces belonging to Pliocene are seen on the plateau surfaces. Gümeli and Ivrindi plateaus led to the erosion of the Miocene erosional surfaces. For this reason, the spreading area of the Miocene erosional surfaces decreased due to the removal of the Miogene surfaces. The uplifting of the plateau surfaces occurred during the Pliocene Period. Pleistocene has caused the rejuvenation of fluvial erosion. For this reason, the streams cut their own valleys and the alluvial deposit in the depression has started to be removed by the rejuvenation of fluvial process. The formation of deep gorges in the Kocaçay, Kocabük, and Kocaav şar streams is related to the incursion of the river valley. It can be stated, that the tectonic movements are responsible for the erosional and depositional surfaces in the study area. Miocene erosional surfaces were developed according to the base level of Miocene Lake. Pliocene erosional surfaces were formed in accordance to the tectonic depression in which alluvial plains are found. The rejuvenation of the fluvial process that controlled tectonic movements, caused the superimposition and antecedents events. The streams established on the sedimentary formation deeply cut their own valley so that the pre-Neogene formation is outcropped along the valleys in some places. The uplifting of the area is responsible for the formation of the deep antecedent valley. The terraces occurring along the valley indicate the lowering of the base levels in accordance with the tectonic activities.

International Symposium on Geography Environment and Culture in the Mediterranean Region

Conclusion The upper part of Kocaçay valley has polycyclic topographic shapes with discordant cover. The relief shapes are closely associated with lithology and structure dominant relief shape is plateau. The topography which is dominant in the research area is young because it is cracked and broken. As of today, the river network which is made out of Kocaçay and its branch, was formed in Pliosen. To date, it has maintained its position in spite of some captures. It can be said that the topographic discordance came into being as a result of the Alp tectonic movements. It can also be said that this situation originates from the traces, embedded meanders, and superimposed gorges that have come into being as a result of the deep erosion of the streams that are the evidence of the young tectonic. The surface of the erosion is seen as the main relief element. Volcanism has come into being in a definite amount and it is the consequence of the Third Period. Carstic formations are represented by lapya which are micro topographic formations. The fluvial erosion period in the upper part of the Kocaçay valley is a wide valley on the surface of which is covered with breaks, which indicate the valley is young.

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