Blue Clay.

This deposit lies between the overlying Greensand and the underlying Globigerina. It is the most fertile sediment on the islands and is essential to the agricultural well-being of the island. It also act as an aquifer, many of the springs on the island rise up between the Upper Coralline limestone and the Blue clay. Such locations have often attracted settlement and are very fertile and productive.

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Blue Clay erodes easily when wet and mantles the underlying hillslopes, making farming possible where the gradient is not too steep. The depositional environment indicated by this sediment is open muddy water between 150 and 100 metres deep.

However this erosion can be extreme and result in undercutting and cliff collapse

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This is the view from the citadel on Gozo. In many parts of Gozo the Upper Coralline limestone has been almost completely denuded exposing the Blue clay which erodes very easily. Here you can see that the blue clay has mantled the hillsides in view covering the underlying Globigerina and Lower Coralline limestone. Note the terracing.

Points to consider:

• How widespread is the blue clay formation on Malta/Gozo?
• Is this resource adequate or under threat?
• What steps are being taken to preserve this resource?
• Do buildings erected on this sediment take adequate account of the sediments properties?
• What is the relationship between the blue clay, the spring line and agricultural sediment?
• How can this sediment be stabilised to prevent or slow down cliff collapse?

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