block subsidence, originally to depths estimated at 6–7 km, largely filled with sediments that range in age as far back as the Permian-Triassic boundary. Some of the sediments are marine carbonates and clays. The faults are upthrusts and overthrusts. Anticlines associated with these faults form traps for petroleum and natural gas, which has been discovered in 52 small fields. Kazakhstan's Mangystau Province has an area of 165,600 square kilometers and a population of 316,847. It is a major oil- and gas-producing region. The city of Aktau was built in Kazakhstan's Mangyshlak Peninsula as a small village to house the region's oil workers in 1961. Over the years a large influx of Russian and Ukrainian oil and chemical workers arrived. Engineers discovered large amounts of crude oil and petroleum in the area in the days of the Soviet Union, and when drilling commenced, much of the area was built up around the industry. Aktau is Kazakhstan's only seaport on the Caspian Sea. From 1964 to 1991 Aktau, which had become a city, bore the name "Shevchenko" in honour of the Ukrainian poet Taras Shevchenko (1814–1861), who had been assigned to the area on military work. The average temperature on January is −3 °C, on July +26 °C. Annual rainfall averages 150 mm. Aktau had a population of 154,500 . Transport Much of the road and railway infrastructure that exists across Central Asia was developed when the areas was in the Soviet Union. As a result, it often disregards existing national borders. After the dissolution of the Soviet Union, this infrastructure has faced decline and degradation. Metallurgy Kazakhstan had started to produce and refine sizable amounts of tin and uranium by the early 1970s. Vanadium and cobalt were, and still are also mined in the south of the country. Uranium was also first produced in Uzbekistan in the 1970s. The city of Zhezkazgan was created in 1938 in connection with the exploitation of the rich local copper deposits. In 1973 a large mining and metallurgical complex was constructed to the southeast to smelt the copper that until then had been sent elsewhere for processing. Other metal ores mined and processed locally are manganese, iron and gold. It is on a reservoir of the Kara-Kengir River and has a population of 90,000 (1999 census). Its urban area includes the neighbouring mining town of Satpayev, total population 148,700. 55% of the population are Kazakhs,