From Alborg E45 exit 31 Støvring south, 519 towards Hadsund 15 km. Store Blåkilde Parkering at the road, 1 km, 15 minutes walk to the spring.
|Dimension:||Y=80 l/s, Ø=12 m, D=5 m, T=7-8 °C.|
|Guided tours:||self guided|
|Address:||Store Blåkilde, 9510 Arden, Tel: +45-.|
|As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
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The Store Blåkilde (Big Blue Spring) is a famous karst spring in Denmark, it even has its own parking lot. The spring is really worth a visit, but not exactly spectacular. It owes its fame to the fact that karst is so rare in Denmark and karst springs are also rare. It was considered Denmark's largest spring, but according to recent research it is the third largest after Lille Blåkilde and Blåhøl. In other words the "small" spring is larger than the "big" spring, which is quite funny. But despite its bigger yield, Lille Blåkilde is less worth seeing. Blåhøl is worth seeing, but it is located on private property and very hard to reach.
The most likely theory is, that water originates from the Madum Sø, 2 km to the north, and drains underground through a water-filled cave to the spring. Madum Sø is a karst lake, as it has no outflow on the surface. The lake is only 20 m higher, so the flow rate is not very high.
The spring has a nice circular main spring with a diameter of 12 m, where turquoise water springs and forms a small river named Blåkilde Bæk. The basin is 4-5 m deep, which is enough for the typical blue colour of limestone rich water, which gave the spring its name. The floor of the basin is loose and very unstable limestone gravel. There is a secondary spring at the first bend of the river. The other, smaller springs are in the river bed and hard to see. The main spring has a yield of 80 l/s, all springs together about 300 l/s.
The area of Rold Skov (Rold Forest) in Northern Jutland is probably the largest karst area in the country. The reason is obviously the salt diapir below, which lifted the rock layers and exposed the Danian limestone, which was quarried in nearby Thingbæk Kalkminer (Thingbæk limestone mine). The karst has karst lakes, dolines, sinking streams, and karst springs. But it is not very well developed, drainage is still mostly above ground, and all the potential caves are still small and completely water-filled.