the span of the last three ice ages. Coastlines: Djursland is surrounded by sea on three sides, and has three corresponding distinct types of coastline. Variation is a common denominator for Djursland's coastal geography, as well as the inland geography. North Coast - The 35 km northern coastline of Djursland comprise all-sand beaches with shallow waters throughout. It stretches east from a shallow delta-like marshy coast where the outlet of Denmark's largest river, the Gudenå, enters Randers Fjord and the sea. The north coast beaches are child-friendly for bathing and paddling, while swimming depths are reached about a hundred metres from the shores. The shallow water heats up quickly in summer. Fishing for flatfish is good, but it takes a boat to reach sufficient fishing depth. East Coast - The 50 km coastline facing Sweden (approximately 100 km to the east across the Kattegat) is stony. The east coast has sufficient swimming depth close to the shore within 5–20 metres from land. The east coast is known among anglers and scuba divers. There are two major exceptions to the stony coastline. One is at the Cliffs of Sangstrup and Karlby where a 5 km stretch of coast consists of up to 12 m high limestone cliffs, similar to the Cliffs of Dover but on a smaller scale. The second exception is Grenå Beach, a sandy 5 km long beach with dunes. The beach lies by the coastal town, Grenå, and is a popular bathing beach. Here and there on Djursland's eastern coast, there are steep inclines caused by active coastal erosion, such as at Gjerrild and Rugaard. South Coast - The southern coastline of Djursland is dominated by bights and inlets, with varied stony and sandy stretches and mixed depth gradients. It is always possible to find bights and coves in shelter for any wind direction within a short driving distance. There are a number of sandy bathing beaches here. The tide is moderate around Djursland, with a difference between ebb and flow usually less than 30 cm. Central Djursland The Kolindsund or Sound of Kolind is a dried-out lake that stretches 30 km east–west into central Djursland. The area was a lake until 1870, and a saltwater sound until the Middle Ages, making it possible to sail into central Djursland. Sand drift closed the estuary to the sea, Kattegat. The lakebed is fertile farmland with constant high yields of