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The Geology of the Maltese Islands S. Bajada. Geological history of the Maltese Islands The rocks started to form about 30 to 25 million years ago. The.

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Presentation on theme: "The Geology of the Maltese Islands S. Bajada. Geological history of the Maltese Islands The rocks started to form about 30 to 25 million years ago. The."— Presentation transcript:

1 The Geology of the Maltese Islands S. Bajada

2 Geological history of the Maltese Islands The rocks started to form about 30 to 25 million years ago. 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. 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.Rock strata were formed over millions of years through continuous accumulation. The south western shore of Malta N. Cardona

3 This uplift was due to pressure exerted by the African plate crashing into the Eurasian plate. 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. The Mediterranean sea was cut off from the rest of the oceans 6 million years ago. These rock strata were uplifted for the first time 10 million years ago.These rock strata were uplifted for the first time 10 million years ago. A satellite image of the Mediterranean Sea

4 This caused the drying up of the sea and thus a land bridge emerged connecting the Maltese Islands with Sicily and Europe. 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. 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.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.The water spilled into the enclosed Mediterranean sea and the Maltese Islands were again isolated from Sicily and mainland Europe. Ghar Dalam Pedley et al.

5 2 million years ago, the Mediterranean experienced another Ice Age. 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. 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. Wied Il-Ghasel and Wied Il-Kbir are examples of such valleys. The Ice Age ended years ago.The Ice Age ended years ago. The changing processes have been rather slow till present day.The changing processes have been rather slow till present day. Wied Hanzira Wied Il-Ghasel Pedley et al. R. Galea

6 The Rocks of the Maltese Islands 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 geological times in a succession of various rock strata. These were deposited throughout different geological times in a succession of various rock strata. These are: These are: Upper Coralline Limestone (Il-Qawwi), Greensands (Il-Gebla s-Safra), Blue Clay (Tafal), Globigerina Limestone (Il-Franka) Lower Coralline Limestone (Zonqor).

7 Upper Coralline Limestone (Il-Qawwi) Greensands (Il-Gebla s-Safra) Blue Clay (Tafal) Globigerina Limestone (Il-Franka) Lower Coralline Limestone (Zonqor)

8 Upper Coralline Limestone Plateau Greensands Blue Clay Globigerina Limestone Lower Coralline Limestone Qammieh, Malta S. Bajada

9 Upper Coralline Limestone This is the youngest rock strata. This is the youngest rock strata. It is a very hard rock It is a very hard rock Terra Rossa soil forms from this rock Terra Rossa soil forms from this rock The UCL is used as spalls for road surfacing. The UCL is used as spalls for road surfacing. Ghar Lapsi elevated sea cave cut into the Upper Coralline Limestone Marfa

10 It can be found mainly in the northern part of Malta forming typical plateaus It can be found mainly in the northern part of Malta forming typical plateaus Upper Coralline Limestone plateau overlying Blue Clay slopes Qammieh Imgiebah Elevated Caves found in the UCL S. Bajada

11 Greensands It has a greenish-yellow colour and when it is exposed it turns into orange. 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 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. It is friable and contains many fragments of fossils. This rock strata is found underneath the Upper Coralline Limestone. This rock strata is found underneath the Upper Coralline Limestone. Greensands found at Had-Dingli N. Cardona

12 Blue Clay This rock is named after its bluish colour This rock is named after its bluish colour It is very soft and erodes quickly giving rise to cone- shaped slopes.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.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.These slopes are turned into terraced fields with rubble walls to hold the soil in place. Blue clay slopes at Qammieh S. Bajada

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

14 Globigerina Limestone This is the thickest layer and can be found in central and the south of Malta. 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. It is harder than the Blue Clay but softer than the Upper Coralline Limestone. Lower Globigerina Limestone A fossil found in Globigerina Limestone S. Bajada

15 It is extracted from quarries and used for building purposes. It is extracted from quarries and used for building purposes. It is also used for sculpture and decorative work in stone. It is also used for sculpture and decorative work in stone. Malta this month ‘95 S. Bajada

16 Lower Coralline Limestone It is the oldest rock layer and forms the base of the entire Maltese rock succession. 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. It is generally found exposed on cliff sides facing the sea, such as Ta’ Cenc (Gozo) and Dingli Cliffs. The Blue Grotto Il-Munqar, Wied Babu Ta’ Cenc Cliffs C. Cardona S. Bajada C. Cardona

17 It is a very hard rock and thus forms a rugged and sharp pointed land surface. It is a very hard rock and thus forms a rugged 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 S. Bajada

18 Conclusion The rock succession of the Maltese Islands takes the form of a simple-layered cake. 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: 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

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


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