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S. Bajada. The Geology of the Maltese Islands. Geological history of the Maltese Islands. The rocks started to form about 30 to 25 million years ago. Originated on the sea bed where sediment, silt and remains of tiny sea creatures were deposited.

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geological history of the maltese islands
Geological history of the Maltese Islands
  • The rocks started to form about 30 to 25 million years ago.
  • Originated on the sea bed where sediment, silt and remains of tiny sea creatures were deposited.
  • Rock strata were formed over millions of years through continuous accumulation.

N. Cardona

The south western shore of Malta

slide3

These rock strata were uplifted for the first time 10 million years ago.

  • This uplift was due to pressure exerted by the African plate crashing into the Eurasian plate.
  • The Mediterranean sea was cut off from the rest of the oceans 6 million years ago.

A satellite image of the Mediterranean Sea

slide4
This caused the drying up of the sea and thus a land bridge emerged connecting the Maltese Islands with Sicily and Europe.
  • Several animals migrated to Malta and some of their remains can be found at Ghar Dalam.
  • 5 million years ago, at the end of an Ice Age, ice melted and so the sea level of the Atlantic Ocean rose.
  • The water spilled into the enclosed Mediterranean sea and the Maltese Islands were again isolated from Sicily and mainland Europe.

Pedley et al.

Ghar Dalam

slide5
2 million years ago, the Mediterranean experienced another Ice Age.
  • This brought a wetter climate in this region and so river valleys formed in the Maltese Islands.
  • Wied Il-Ghasel and Wied Il-Kbir are examples of such valleys.

R. Galea

Wied Hanzira

Wied Il-Ghasel

  • The Ice Age ended 10 000 years ago.
  • The changing processes have been rather slow till present day.

Pedley et al.

the rocks of the maltese islands
The Rocks of the Maltese Islands
  • All the Maltese rocks are sedimentary.
  • Five different rocks were formed.
  • These were deposited throughout different geological times in a succession of various rock strata.
  • These are:

Upper Coralline Limestone (Il-Qawwi),

Greensands (Il-Gebla s-Safra),

Blue Clay (Tafal),

Globigerina Limestone (Il-Franka)

Lower Coralline Limestone (Zonqor).

slide7

Greensands (Il-Gebla s-Safra)

Lower Coralline Limestone (Zonqor)

Upper Coralline Limestone (Il-Qawwi)

Blue Clay (Tafal)

Globigerina Limestone (Il-Franka)

slide8

Upper Coralline Limestone Plateau

Greensands

Blue Clay

Globigerina Limestone

Lower Coralline Limestone

Qammieh, Malta

S. Bajada

upper coralline limestone
Upper Coralline Limestone
  • This is the youngest rock strata.
  • It is a very hard rock
  • Terra Rossa soil forms from this rock
  • The UCL is used as spalls for road surfacing.

Marfa

Ghar Lapsi elevated sea cave cut into the Upper Coralline Limestone

slide10

Upper Coralline Limestone plateau overlying Blue Clay slopes

  • It can be found mainly in the northern part of Malta forming typical plateaus

Qammieh

Elevated Caves found in the UCL

S. Bajada

Imgiebah

S. Bajada

greensands
Greensands
  • This rock strata is found underneath the Upper Coralline Limestone.
  • It has a greenish-yellow colour and when it is exposed it turns into orange.
  • It is the thinnest layer and reaches a maximum thickness of 11 metres at Il-Gelmus in Gozo
  • It is friable and contains many fragments of fossils.

N. Cardona

Greensands found at Had-Dingli

blue clay
Blue Clay
  • This rock is named after its bluish colour
  • It is very soft and erodes quickly giving rise to cone-shaped slopes.
  • This rock can be found in the north western part of Malta and north east of Gozo.
  • These slopes are turned into terraced fields with rubble walls to hold the soil in place.

S. Bajada

Blue clay slopes at Qammieh

globigerina limestone
Globigerina Limestone

Lower Globigerina Limestone

  • This is the thickest layer and can be found in central and the south of Malta.
  • It is harder than the Blue Clay but softer than the Upper Coralline Limestone.

S. Bajada

S. Bajada

A fossil found in Globigerina Limestone

S. Bajada

slide15

S. Bajada

  • It is extracted from quarries and used for building purposes.

Malta this month ‘95

  • It is also used for sculpture and decorative work in stone.

Malta this month ‘95

lower coralline limestone
Lower Coralline Limestone
  • It is the oldest rock layer and forms the base of the entire Maltese rock succession.
  • It is generally found exposed on cliff sides facing the sea, such as Ta’ Cenc (Gozo) and Dingli Cliffs.

Ta’ Cenc Cliffs

S. Bajada

C. Cardona

C. Cardona

The Blue Grotto

Il-Munqar, Wied Babu

C. Cardona

slide17
It is a very hard rock and thus forms a rugged and sharp pointed land surface.
  • It reaches a maximum thickness of 140 metres.

The top layer of the Lower Coralline Limestone is made from a scutella bed

Dwejra

N. Cardona

S. Bajada

  • Its colour ranges from, pale grey to red and buff.

N. Cardona

Dwejra, Gozo

conclusion
Conclusion
  • The rock succession of the Maltese Islands takes the form of a simple-layered cake.
  • Each rock layer has distinct characteristics such as thickness and hardness due to their formation under various conditions:

Depth of sea

Sunlight

Distance from nearest land

Direction and force of sea currents

Different species of organisms.

N. Cardona

references
References
  • Azzopardi, A. 1995. A New Geography of the Maltese Islands, St. Aloysius College, Malta
  • Pedley, M Clarke, M.H and Galea, P. 2002. Limestone Isles in a Crystal Sea: the Geology of the Maltese Islands, P.E.G publishers, San Gwann.