Environmental- rocks

• The three types of rocks:

  Igneous - ex. Graphite

  Sedimentary - ex. Limestone

  Metamorphic - ex. marble
• The rock cycle

  rocks are formed, destroyed and formed once again. For igneous rock to form melting is required, for metamorphic rock to form heating and pressure is required and for sedimentary rocks to form, weathering and erosion is needed.
• What are Igneous rocks?

  These types of rocks are formed in volcanic areas when lava erupts it cools and forms rocks. Igneous rocks have crystals in them. The rate of cooling determines the size of the crystals.
• What are Sedimentary rocks?

  These are formed from sediments. Sediments are remains of organisms together with mud silt and clay. They contain fossils.
• What are Metamorphic rocks?

  Metamorphic rocks were previously, Igneous or Sedimentary rocks which have been in subject to extreme heat and pressure, were in a change of composition and structure
• What are fossils?

  These are remains from dead plants and animals which were imprinted in the rock. It gives us and introduction about past environments.
• How were the Maltese islands formed?

  They were formed due too the sedimentation process.
• How did the sedimentation process happen?

  Happens when rock fragments and other remains are deposited on the sea bed to be cemented forming rock layers.

  The African plates are hitting the Eurasian plate which caused the uplift of land above sea level.

  The changing levels in the Mediterranean sea.
• The Maltese rocks in order:

  Upper-coralline limestone

  greensands

  Blue clay

  Globigerina limestone

  Lower-coralline limestone
• What are the characteristics, landforms, sage and location of the Upper-coralline limestone?

  Its hard, the youngest and forms red type soil. Its land forms are plateaux and caves. It is used as spalls and roadmaking and found at Comino.
• What are the characteristics, landforms, sage and location of the Green sands?

  Is the thinnest layer, easily eroded, is yellowish in colour and contains fossils. It has no landforms or usage but is found in Glemus hill Gozo.
• What are the characteristics, landforms, sage and location of the Blue clay?

  It is impermeable, grey in colour and forms the water table. It forms the Talus slopes and is used for pottery and found in Ghajn Tuffieha.
• What are the characteristics, landforms, sage and location of the Globigerina limestone?

  It is the most common rock in Malta and is easily cut, it forms planes and hills and is used to build houses and stables. It is found in Mqabba and Qrendi.
• What are the characteristics, landforms, sage and location of the Lower-coralline limestone?

  It is very strong and the oldest layer, it forms cliffs and landscape it is used for breakwater building and found in bahar ic-caghaq.
• What is the Karst landscape?

  Its a rugged landscape full of cavities which are filled with soil where the garrigue ecosystem grows.
• What are the different types of weathering?

  Freeze-thaw weathering

  Onion-skin weathering

  Chemical weathering

  Biological weathering

  Physical weathering
• What is physical weathering?

  This includes a change in temperature.
• What is freeze-thaw weathering?

  This is also known as frost shattering. A crack in the rock is filled with water. at night when the temperature goes below 0oC the water will become ice and it will expand. This will cause the rock to start to shatter. Eventually when this keeps happening repeatedly thee rock will shatter.
• What is onion-skin weathering?

  Happens in warm climates. During the day, the sun heats the rock and it will expand, during the night, the temperature drops and the rock will contract. this continuous process will cause the rock to peel off like an onion.
• What is chemical weathering?

  Involves chemical reactions that change the composition of rocks- example acid rain.
• What is biological weathering?

  Involves the breakdown of rock due to plant roots and burrowing of animals.