twice a year in the past, but nowadays it has become less and less likely thanks to global warming. Hail and lightning storms are not uncommon in Fall and Spring and have devastating effects on crops and the farming-dependent economy of the county. Western air masses from the Mediterranean and Black Sea are cause autumn and winter rains in the province, and Sudanese and Red Sea and Saudi Arabia currents are also effective in winter and spring rains and cause warm weather in summer. The vast plains of Iraq create a low-pressure high-temperature low-humidity weather cell over the area. Seymareh Landslide In prehistoric times, a huge landslide occurred in the south eastern parts of Kabir Kuh range. The incident is described in an article on Royal Geographical Society, published in 1937 by Harrison and Falcon. Based on their observations, the landslide is in area and in thickness; amounting to a body of material of about , some of which is found around from their original location. The reason for this colossal event is very likely to have been a catastrophic earthquake. Due to its enormity, the Seymareh Landslide is believed to be the largest one recorded in the eastern hemisphere. Economy The economy of Darreh Shahr is mostly based on agriculture and animal husbandry. As of February 2018, Darreh Shahr farmers produce more than 190,000 tons of agricultural and 23,000 tons of livestock products annually. Darreh Shahr has about of farming irrigated and dry lands. The agriculture market in Darreh Shahr is worth around US$17.7m. Darreh Shahr is a large producer of daffodils with about of cultivated farms and an average annual production of 7 million flowers, most of which is marketed in cities of Tehran, Isfahan, Ahvaz and Arak. The majority of the people living in urban areas, especially Darreh Shahr, work in construction and services trades sector. As the county seat, Darreh Shahr hosts almost all of the government offices of the county, therefore many people work for the government. Despite the rather solid agriculture sector, the industry sector is emerging and small. Darreh Shahr Industrial City hosts a number of SMEs, the most prominent of which are Seif Ghostar Food Products Company and Madakto Steel Cord Company, the first and only steel cord producer in Iran. Darreh Shahr Flour Factory, established in 1993, is a wheat flour milling plant with an installed capacity of 120 metric tons