Turkey spans two continents: about 97 per cent of its roughly 783,000 km² lies in Asia, on the Anatolian peninsula, and 3 per cent in Europe, in Eastern Thrace, with the Bosphorus, the Sea of Marmara and the Dardanelles between them. Seas wrap it on three sides, the Black Sea to the north, the Aegean to the west and the Mediterranean to the south, and it borders eight countries from Greece and Bulgaria to Iran and Iraq. Its physical regions are a high central plateau, the Anatolian Plateau, framed by the Pontic Mountains along the Black Sea and the Taurus Mountains along the Mediterranean; fertile Aegean valleys in the west; and a rugged eastern highland where the two ranges converge. The land rises steadily eastward to Mount Ararat, the highest point at 5,137 m. The longest river entirely within Turkey is the Kızılırmak (1,355 km); the Sakarya, the Euphrates, the Tigris and the Aras are other major rivers, and Lake Van is the largest lake. The country is crossed by the North Anatolian Fault, whose earthquakes are among Turkey’s most dangerous natural hazards.
One road shows most of this in a single journey. The European route E80, numbered D.100 for much of its Turkish length, runs from the Bulgarian border at Kapıkule to the Iranian border at Gürbulak, beneath Ararat. Here are the landforms it meets, west to east.
Kapıkule and Edirne: Thrace’s Rolling Farmland
The journey begins at Kapıkule, the border post opposite Bulgaria’s Kapitan Andreevo. Together they form the busiest land border crossing in Europe: about 2.4 million vehicles and 4 million people a year, roughly 35 per cent of all vehicles crossing Turkey’s land borders. Edirne, 20 km from the Bulgarian border and 7 km from the Greek one, stands where the Meriç (Maritsa) and Tunca rivers flow around its west and south sides. It was the second Ottoman capital, from the 1360s until 1453.
East of Edirne the motorway crosses Eastern Thrace, a rolling plateau well suited to farming that makes up just 3 per cent of Turkey’s land but holds roughly 12 to 15 per cent of its people, depending on the source. Its main river, the Ergene, rises on the Strandzha hills near the Black Sea and flows 281 km to join the Meriç near İpsala; at Uzunköprü it is crossed by a stone bridge begun in 1426/27, finished in 1443/44 and claimed to be the longest stone bridge in the world; it was 1,392 m long with 174 arches when completed. The road passes Lüleburgaz and Çorlu and reaches the Marmara shore at Silivri.
Istanbul and the Bosphorus: Crossing from Europe to Asia
At Istanbul the route crosses the Bosphorus, the 31 km strait that links the Black Sea with the Sea of Marmara and forms one of the boundaries between Europe and Asia. It is the narrowest strait in the world used by international shipping, with a width ranging from 3,420 m at its widest to just 700 m between Kandilli Point and Aşiyan. Istanbul’s metropolitan population of about 17 million spreads inland from both shores.
According to one widely discussed hypothesis, rising seas at the end of the last ice age burst through the Bosphorus into what was then a freshwater Black Sea lake. Once on the Asian side, the E80 follows the northern shore of the Sea of Marmara east, past Gebze; there is more on the strait itself in our guide to the Bosphorus.
The Gulf of İzmit and Lake Sapanca: On the North Anatolian Fault
East of Gebze the road runs along the Gulf of İzmit, the narrow eastern arm of the Sea of Marmara, about 48 km long and only 2 to 10 km wide. The gulf is crossed by the North Anatolian Fault, the boundary along which the Anatolian block slides west past the Eurasian plate. The fault runs some 1,200 to 1,500 km from the Karlıova junction in the east into the Aegean, passing about 20 km south of Istanbul, and from here almost to Erzincan the E80 follows it.
Beyond İzmit the road skirts Lake Sapanca, a freshwater lake about 16 km long, 5 km wide and 52 to 61 m deep by different surveys, lying in a tectonic hollow between the gulf and the Adapazarı plain at just 33 m above sea level. At 03:01 on 17 August 1999 the fault ruptured here in the magnitude 7.6 İzmit earthquake, which killed at least 18,373 people; the rupture jumped a step-over beneath Sapanca and ran on east. Just past the lake the road crosses the Sakarya, Turkey’s third-longest river at 824 km, known to the Greeks as the Sangarios, flowing north to the Black Sea.
Mount Bolu and Gerede: Climbing into the Köroğlu Mountains
After Hendek and Düzce the motorway leaves the coastlands and climbs into the mountains north of Ankara. The Mount Bolu Tunnel, 3.1 km long with twin three-lane bores, takes it under Bolu Mountain between Kaynaşlı and Yumrukaya. The tunnel crosses the North Anatolian Fault itself: on 12 November 1999, while it was still under construction, the magnitude 7.2 Düzce earthquake damaged it and the viaducts leading to it. It finally opened in 2007.
Beyond Bolu rise the Köroğlu Mountains, which run from the Sakarya to the Kızılırmak along the fault. Their highest point, Köroğlu Tepesi, is a 2,499 m andesite plateau south of Bolu with the ski resorts of Kartalkaya and Sarıalan. At Gerede the E80 rejoins the old D.100. This stretch is the scene of the 1944 Bolu–Gerede earthquake, which ruptured about 180 km of the fault across five segments.
Ilgaz and Osmancık: Over the Pontic Ranges to the Kızılırmak
East of Gerede the road reaches Ilgaz, on the southern foot of the Ilgaz Mountains. These belong to the Pontic system, which along the western Black Sea forms three ranges parallel to the coast; the Ilgaz range is the eastern part of the second, about 100 km inland, 150 km long and 30 km wide. Its summit, Büyükhacet Tepe, reaches 2,587 m. The road then runs through Tosya, a town on the fault that was hit by a major earthquake in 1943.
At Osmancık the route crosses the Kızılırmak, the “Red River”, known to the ancient world as the Halys. At 1,355 km it is the longest river flowing entirely within Turkey. It rises in eastern Anatolia, swings in a great arc, the Halys bend, across the central plateau north-east of the salt lake Tuz Gölü, and reaches the Black Sea through a delta north-west of Samsun. To the Hittites it was the Maraššantiya and marked the western edge of their core land, and later it divided Lydia from Persia. Osmancık still sits on the fault and is known for its rice, a strain called Osmancık-97.
Erzincan: The Upper Euphrates Basin
Past Merzifon and Refahiye the D.100 climbs into eastern Anatolia and drops into the basin of Erzincan. Here it meets the Euphrates. The western branch of the river, the Karasu (“black water”), about 450 km long, rises on Dumlu Dağ in Erzurum province, drains the Erzurum plain and flows west through Erzincan province before swinging south through a deep canyon into the Keban Dam lake. The Euphrates goes on through Syria and Iraq, about 2,780 km in all, the longest river in West Asia.
Erzincan is also where the great twentieth-century sequence on the North Anatolian Fault began. On 27 December 1939 a magnitude 7.8 earthquake ruptured some 360 km of the fault, shifting the ground sideways by up to 3.7 m and killing 32,968 people, the worst natural disaster in twentieth-century Turkey. Seven earthquakes over magnitude 7 have followed, each striking further west, a sequence that includes İzmit in 1999. The fault zone is explained in detail in our North Anatolian Fault guide.
Erzurum at 1,900 m: Turkey’s High Eastern Plateau
Beyond Aşkale the road reaches Erzurum, on a high plain about 1,900 m above sea level, close to where the Pontic and Anti-Taurus mountains converge into the highland historically called the Armenian Highland. Winters here are far harsher than on the central plateau: Erzurum’s January nights average around −16 °C, it recorded −37.2 °C on 28 December 2002, and snow can lie for 120 days a year in the eastern mountains. Palandöken Mountain, 3,271 m, rises only 10 km from the city centre and carries Turkey’s longest ski run; the city hosted the 2011 Winter Universiade.
The Anti-Taurus here is a watershed for three great rivers. The Euphrates and Tigris flow south to the Persian Gulf, while the Aras flows east, along the borders with Armenia, Nakhchivan and Iran, for 1,072 km to join the Kura and reach the Caspian Sea.
Doğubayazıt and Mount Ararat: The Road Ends at Gürbulak
After Ağrı, the D.100 reaches Doğubayazıt, a town at 1,625 m below the country’s highest mountain. Mount Ararat, officially Mount Ağrı, is a dormant compound volcano with two cones: Greater Ararat, 5,137 m, the highest peak in Turkey and the Armenian highlands, and Little Ararat, 3,896 m. The massif is about 35 km wide at its base and permanently snow-capped. The first recorded ascent was made in 1829 by Friedrich Parrot, Khachatur Abovian and four others. The mountain stands near the meeting point of Turkey, Iran, Armenia and Azerbaijan’s Nakhchivan exclave; it became part of Turkey under the 1921 treaties of Moscow and Kars and remains the principal national symbol of Armenia.
Beyond Doğubayazıt, the E80 ends at Gürbulak, a village of about 2,200 people and the crossing into Iran. From Kapıkule the road has climbed from the plains of Thrace to the edge of the Armenian Highland, following a fault line most of the way. The plateau that the E80 skirts to the north, around Ankara and Konya, is a journey of its own, described in our guide to the Anatolian Plateau.