The seas and the lands have divided the lacework geography of Istanbul into four regions. Old Istanbul City and Galata in the shores of Golden Horn (Haliç) and previously different village now united residential districts are located along the straits of Bosphorus. As the smallest sea of the world, inhabited places along the shores of Marmara Sea shows the magnitude that the city has reached. The Old City is spread over the seven hills of the triangular peninsular surrounded by 22 km of city walls.
Having been in the center of Old World, Istanbul is an important megapole with its historical monuments and wonderful natural scenery. Established where Asian and European Continents were split with a narrow strait, built on two continents, it is the only city that the sea goes through. With its history of over 2500 years, Istanbul had become an important commerce center because of its establishment in this strategic location where land meets sea. Historical city of Istanbul is located on a peninsular, surrounded by Marmara Sea, Bosphorus Straits and Golden Horn.
Istanbul is located in the coordinates of 280 01’ and 290 55’ East longitudes and 410 33’ and 400 28’ North latitudes. While joining Black Sea and Marmara Sea, Istanbul Straits divides Asian and European Continent as well as Istanbul City. The province is bordered by high summits of Kocaeli Mountain Ranges in the East, by Marmara Sea in the South and waterline of Ergene Basin in the West.
Being in the junction where all the roads reach sea, easily defendable peninsular, ideal climate, very rich and generous nature, strategic control of the Straits and strategic location of being in the center of world are all fortune of Istanbul. Istanbul has been of much significance throughout history because of being in the joining point of two continents, being the gateway to the hot climates and oceans and being outer reach of Silk Road extending to Europe.
The city had become the capital city of three great empires, namely Roman, Byzantine and Ottoman Turks; and, was ruled by more than 120 emperor and sultans over 1600 years. Istanbul is the only city that has all these features. During its development, the city underwent expansion for four times, which all of them were westward. In the 5th century, there was an Istanbul which was surrounded by city walls of Romans and built over 7 hills.
But, the foundation of today’s Istanbul was grounded in 7th century B.C. Rebuilt by Emperor Constantine in 4th century A.D., the city had been transformed to capital city; since then, it had preserved that title for almost 16 centuries by hosting the capital cities of Rome, Byzantine and Ottomans. Being one of the centers of Christianity starting with Emperor Contantine, Istanbul was considered as one of the most important cities of Islamic World, after its conquest in 1453 by Ottomans.
During these periods of Empires’ reign, it was also the administrative center of the religions, undertaking the Patriarchy of Eastern Christianity till today, rising the first biggest church and monasteries of Christian World on top of pagan temples. Istanbul had assumed its Islamic character with decoration of artifacts, mosques, palaces, schools, baths and other facilities; and current ruins of churches had been repaired, restored and converted to mosques in almost a century after its conquest.
TOPOGRAPHY (GEOMORPHOLOGY AND TOPOGRAPHIC THRESHOLDS)
Istanbul Metropolitan is located on Kocaeli and Catalca Peninsulas. Both peninsulas are decayed plateaus. Istanbul and its surrounding, while a bay of Sarmat inner sea at the end of 3rd Period of Miosen Era, in Pilosen Era sea was withdrawn, lands surfaced; later, after the long period of erosion by the decaying of rivers and winds, a wide peneplain appeared with the heights lost and quartzite hills left. And valley in place of Bosphorus Straits was widened. Later, with the rise of northern part in the east of Bosphorus Straits, and the rise of southern part in this peneplain, sea routes changed and decaying by water increased because of the increasing change in the slope of river valleys; big rivers in the east flooded into Black Sea and in the west flooded into Marmara Sea.
In the result of above mentioned geologic movements, the field of Istanbul Metropolitan assumed a look of a worn-out peneplain.
Being grouped as geomorphologic units, valleys, plains, height (light wave heights), higher grounds have no distinct shapes in Istanbul Metropolitan area because of the above-explained reasons. Quartzite hills (Aydos, Kayisdagi, Alemdag, etc.) in (Kocaeli Plateau) resistant to decaying and higher grounds starting from the east of Gebze-Omerli Damn route and continuous rise (+350m) take place in the east of Istanbul Metropolitan area. In this peninsular, ‘water section line’ is closer to Marmara sea shores. The remaining of peneplain includes wider valley base and light waved areas where the flowing direction of the rivers are towards Black Sea.
In the western part (Çatalca or Thrace Peneplain), there is again a peneplain with wide based river valleys, apart from a couple of heights rising up to 200m in some part in Bosphorus – Buyukcekmece – Karacakoy route. But, in this peninsula, ‘water section line’ is closer to the Black Sea. Rivers flow more into Golden Horn, Buyukcekmece and Kucukcekmece Lakes and Marmara Sea. Terkos Lake, however, takes its water mostly from Istiranca Mountains in the northwest. Except for the heights of Istiranca Mountains that are rising up to 350m at some points, there are hills and ridges ranging between 200-350m in the west of Catalca and Kestanelik-Belgrad Village routes.
There is no definite climate type for the whole Istanbul Province. Because of its geographic location and physical geographic features, it carries different climate features than the ones in the same latitudes.
Being in the low-pressure and high-pressure zones which repeats twice in order, starting from equator on the earth, Istanbul (41 degree north latitude and 29 degree east longitude, Istanbul is in the borders of subtropical high pressure zone and cold-warm part of low-pressure zone; or terrestrial (dry) alize winds and west winds (humid and rainy) of sea. With the movement of earth, various climate conditions are experienced in winter and summer.
Throughout the year, three types of weather is dominant in Istanbul. One is coming from north and south and the other is more calm weather type. Weather types of east-west direction bound are insignificant. Among these three types of weather, highest frequency (most frequent blowing) one comes along when the northern winds are dominant. There are four phases according to the seasons; two transition phases of one short and one long with hot and cold periods.
Natural flora of Istanbul Metropolitan area is composed of forest, maquis, pseudo-maquis (adapted to Black Sea climate, transformed, characters of humid, group of tree-like maquis plants) and sea side plants. Adapted to the plant groups in Catalca and Kocaeli have developed their “humid” species in the north and “dry” species in the south.
Kocaeli Peninsula’s pseudo-maquis contains the elements of cornelian cherry, hazelnut, deer thorn (local name), sloe bushes, medlar, white birch, elderberry, sumach, wolf’s bossom (local name) and bear’s grape (local name) whose leaves are falling in the winter; and, of akcakesme, strawberry, heath, daphne (laurel), broom, juniper tar (cad oil), kermes oak, rock rose and gum mastic.
Tree types characterizing the humid forests are more of chestnut, beech, hornbeam, pedunculate oak (English oak) located more in the northeast of Bosphorus Straits, north of Alemdag and surrounding Polonezkoy. In the area between Riva Creek and Gokdere in Agva pedunculate oak in the west and Hungarian oak in the east are the dominant ones.
Flora is not directly related climate only, but also related to the soil type. While all beech groups are populated on unslaked lime brown forest soil, oak and chestnut trees can be seen on brown forest soils.
Translated by Mr. Irfan KOKSAL