Globigerina Limestone

Globigerina Limestone

Layer	4 of 5
Blocks	sandstone, smooth sandstone, stone, tuff
Thickness	25–200 m
Above	Blue Clay
Below	Lower Coralline Limestone

The pale Lower Globigerina round the Azure Window

Globigerina Limestone (Maltese: Franka) is the soft, pale limestone of Malta's rock layers, and the islands' traditional building stone. It lies under the Blue Clay and over the Lower Coralline Limestone.

In the world

The layer has three members, from the bottom up:

Member	Main block	Second block	Beds
Lower Globigerina	sandstone	smooth sandstone	cream to yellow, thick beds
Middle Globigerina	stone	tuff	pale grey marl, very thin beds
Upper Globigerina	sandstone	smooth sandstone	yellow, with a grey marl middle

• Marker beds: thin packed-mud lines mark the phosphorite pebble beds at the top of the Lower and the base of the Upper member, as in real cliffs.
• Thickness: 25–200 m in total.
• Local colour: at Dwejra Point, round the Azure Window, the Lower Globigerina is whitish-grey (smooth sandstone and stone), as photos show.

Where to see it

• Santa Luċija, near Kerċem on Gozo: bare yellow Upper Globigerina sandstone, with a dark packed-mud marker line a few blocks down.
• The Azure Window: the pale Lower Globigerina platform round the arch.

Coordinates

• Santa Luċija: /tp @s -14385 173 -12719
• Azure Window platform: /tp @s -17250 80 -13630

Mining

Unlike vanilla sandstone, the Globigerina carries ores.

See also

• Rock layers
• Lower Coralline Limestone: the layer below