The Geology of the The Geology of the Maltese IslandsMaltese Islands

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Geological history of the Maltese IslandsGeological history of the Maltese Islands

• The rocks started to form about 30 to 25 million The rocks started to form about 30 to 25 million years ago.years ago.

• Originated on the sea bed where sediment, silt Originated on the sea bed where sediment, silt and remains of tiny sea creatures were and remains of tiny sea creatures were deposited.deposited.

• Rock strata were formed Rock strata were formed over millions of years over millions of years through continuous through continuous accumulation.accumulation.

The south western shore of Malta

N. Cardona

• This uplift was due This uplift was due to pressure exerted to pressure exerted by the African plate by the African plate crashing into the crashing into the Eurasian plate.Eurasian plate.

• The Mediterranean The Mediterranean sea was cut off sea was cut off from the rest of the from the rest of the oceans 6 million oceans 6 million years ago.years ago.

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

A satellite image of the Mediterranean Sea

• This caused the drying up of the sea and thus a This caused the drying up of the sea and thus a land bridge emerged connecting the Maltese land bridge emerged connecting the Maltese Islands with Sicily and Europe.Islands with Sicily and Europe.

• Several animals migrated to Malta and some of Several animals migrated to Malta and some of their remains can be found at Ghar Dalam.their remains can be found at Ghar Dalam.

• 5 million years ago, at the end 5 million years ago, at the end of an Ice Age, ice melted and of an Ice Age, ice melted and so the sea level of the Atlantic so the sea level of the Atlantic Ocean rose.Ocean rose.

• The water spilled into the The water spilled into the enclosed Mediterranean sea enclosed Mediterranean sea and the Maltese Islands were and the Maltese Islands were again isolated from Sicily and again isolated from Sicily and mainland Europe.mainland Europe. Ghar Dalam

Pedley et al.

• 2 million years ago, the Mediterranean experienced 2 million years ago, the Mediterranean experienced another Ice Age.another Ice Age.

• This brought a wetter climate in this region and so river This brought a wetter climate in this region and so river valleys formed in the Maltese Islands.valleys formed in the Maltese Islands.

• Wied Il-Ghasel and Wied Il-Kbir are examples of such Wied Il-Ghasel and Wied Il-Kbir are examples of such valleys.valleys.

• The Ice Age ended 10 000 years The Ice Age ended 10 000 years ago. ago.

• The changing processes have The changing processes have been rather slow till present day.been rather slow till present day.

Wied Hanzira

Wied Il-Ghasel

Pedley et al.

R. Galea

The Rocks of the Maltese The Rocks of the Maltese IslandsIslands• All the Maltese rocks are sedimentary.All the Maltese rocks are sedimentary.• Five different rocks were formed.Five different rocks were formed.• These were deposited throughout different These were deposited throughout different

geological times in a succession of various geological times in a succession of various rock strata.rock strata.

• These are: These are: Upper Coralline Limestone (Upper Coralline Limestone (Il-QawwiIl-Qawwi),),Greensands (Greensands (Il-Gebla s-SafraIl-Gebla s-Safra), ), Blue Clay (Blue Clay (TafalTafal),),Globigerina Limestone (Globigerina Limestone (Il-FrankaIl-Franka) ) Lower Coralline Limestone (Lower Coralline Limestone (ZonqorZonqor).).

Upper Coralline Limestone (Il-Qawwi)

Greensands (Il-Gebla s-Safra)

Blue Clay (Tafal)

Globigerina Limestone (Il-Franka)

Lower Coralline Limestone (Zonqor)

Upper Coralline Limestone Plateau

Greensands

Blue Clay

Globigerina Limestone

Lower Coralline Limestone

Qammieh, MaltaS. Bajada

Upper Coralline Upper Coralline LimestoneLimestone

• This is the youngest This is the youngest rock strata.rock strata.

• It is a very hard rockIt is a very hard rock

• Terra Rossa soil Terra Rossa soil forms from this rockforms from this rock

• The UCL is used as The UCL is used as spalls for road spalls for road surfacing.surfacing.

Ghar Lapsi elevated sea cave cut into the Upper Coralline Limestone

Marfa

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

Upper Coralline Limestone plateau overlying Blue Clay slopes

Qammieh

Imgiebah

Elevated Caves found in the UCL

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GreensandsGreensands

• It has a greenish-yellow It has a greenish-yellow colour and when it is colour and when it is exposed it turns into exposed it turns into orange.orange.

• It is the thinnest layer and It is the thinnest layer and reaches a maximum reaches a maximum thickness of 11 metres at thickness of 11 metres at Il-Gelmus in GozoIl-Gelmus in Gozo

• It is friable and contains It is friable and contains many fragments of many fragments of fossilsfossils..

• This rock strata is found underneath the Upper This rock strata is found underneath the Upper Coralline Limestone.Coralline Limestone.

Greensands found at Had-Dingli

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Blue ClayBlue Clay• This rock is named after its bluish colourThis rock is named after its bluish colour

• It is very soft and erodes It is very soft and erodes quickly giving rise to cone-quickly giving rise to cone-shaped slopes.shaped slopes.

• This rock can be found in This rock can be found in the north western part of the north western part of Malta and north east of Malta and north east of Gozo.Gozo.

• These slopes are turned These slopes are turned into terraced fields with into terraced fields with rubble walls to hold the soil rubble walls to hold the soil in place.in place.Blue clay slopes at

Qammieh

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• Blue Clay is impermeable and so it holds Blue Clay is impermeable and so it holds water which can be used for irrigation water which can be used for irrigation purposes.purposes.

Globigerina LimestoneGlobigerina Limestone

• This is the thickest layer and can be found This is the thickest layer and can be found in central and the south of Malta.in central and the south of Malta.

• It is harder than the Blue Clay but softer It is harder than the Blue Clay but softer than the Upper Coralline Limestone.than the Upper Coralline Limestone.

Lower Globigerina Limestone

A fossil found in Globigerina Limestone

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

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

Malta this month ‘95

Malta this month ‘95

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Lower Coralline LimestoneLower Coralline Limestone

• It is the oldest rock It is the oldest rock layer and forms the layer and forms the base of the entire base of the entire Maltese rock Maltese rock succession.succession.

• It is generally found It is generally found exposed on cliff exposed on cliff sides facing the sides facing the sea, such as Ta’ sea, such as Ta’ Cenc (Gozo) and Cenc (Gozo) and Dingli Cliffs.Dingli Cliffs. The Blue

GrottoIl-Munqar, Wied Babu

Ta’ Cenc Cliffs

C. Cardona

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C. Cardona

C. Cardona

• It is a very hard rock and thus forms a rugged It is a very hard rock and thus forms a rugged and sharp pointed land surface.and sharp pointed land surface.

• It reaches a maximum thickness of 140 metres.It reaches a maximum thickness of 140 metres.

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

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

Dwejra

Dwejra, Gozo

N. Cardona

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ConclusionConclusion

• The rock succession of the Maltese Islands The rock succession of the Maltese Islands takes the form of a simple-layered cake.takes the form of a simple-layered cake.

• Each rock layer has distinct characteristics Each rock layer has distinct characteristics such as thickness and hardness due to such as thickness and hardness due to their formation under various conditions:their formation under various conditions:Depth of seaDepth of seaSunlightSunlightDistance from nearest landDistance from nearest landDirection and force of sea currentsDirection and force of sea currentsDifferent species of organisms. Different species of organisms.

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ReferencesReferences• Azzopardi, A. 1995. A New Geography of the Azzopardi, A. 1995. A New Geography of the

Maltese Islands, St. Aloysius College, MaltaMaltese Islands, St. Aloysius College, Malta

• Pedley, M Clarke, M.H and Galea, P. 2002. Pedley, M Clarke, M.H and Galea, P. 2002. Limestone Isles in a Crystal Sea: the Geology of Limestone Isles in a Crystal Sea: the Geology of the Maltese Islands, P.E.G publishers, San the Maltese Islands, P.E.G publishers, San Gwann.Gwann.