5 LESSON_Q1

• Fossils


  Preserved remains or traces of organisms from the remote past
• Glossopteris


  • Extinct plant with fossils found in continents now separated by oceans
• Mesosaurus and Lystrosaurus


  Freshwater reptiles with fossils found in continents now separated by oceans
• Fossils of Mesosaurus and Lystrosaurus found in South America and Africa, 4,800 km apart with an ocean in between
• Fossils of Mesosaurus and Lystrosaurus also found in Antarctica
• Fossils of plants and animals found in continents now separated by oceans


  Indicates the continents were once connected
• Continents fit together like a jigsaw puzzle, with the edges of one continent matching the edges of another
• South America and Africa fit together, as do India, Antarctica, and Australia, and Eurasia and North America
• Fossils of extinct plants and animals from the remote past have been found
• Fossils of Glossopteris plant

  • Found in 250 million year old rocks in Southern Africa, Australia, India, and Antarctica
• The large seeds of Glossopteris plant could not have travelled long distances by wind or ocean waves
• Fossils of Mesosaurus and Lystrosaurus


  • Found in South America and Africa, 4,800 km apart with an ocean in between
• It is impossible for these freshwater reptiles to swim across vast oceans
• Fossils of Mesosaurus and Lystrosaurus were also found in Antarctica
• If Antarctica was in its current position

  The low temperatures would have made it impossible for these reptiles to exist there
• If Antarctica was not in its current position long ago

  It would explain the presence of these reptile fossils
• Rock formations in Africa line up with those in South America as if they were once a long mountain range
• The folded Cape mountains of South America and Africa line up perfectly
• Gondwana system of sediments


  • Found in India, Madagascar, Africa, Antarctica, Falkland Island, and Australia
• The Gondwana sediments have thick tillite at the base, indicating widespread and sustained glaciation
• The similarity of the Gondwana sediments shows these landmasses had exceptionally similar origins
• The presence of abundant placer gold deposits along the Ghana coast, with the source rocks absent in the area, indicates the gold came from the Brazil plateau when the two continents were beside each other
• The widespread distribution of Permo-Carboniferous glacial sediments in South America, Africa, Madagascar, Arabia, India, Antarctica and Australia was evidence for the theory of continental drift
• The continuity of glaciers, inferred from glacial striations and tillites, suggested the existence of the supercontinent of Gondwana
• The oldest rocks in the Atlantic Ocean are around 200 million years old
• The Atlantic Ocean began to form around 200 million years ago
• Scientists can determine the age of the seafloor by examining the changing magnetic field of the Earth
• Rocks crystallizing from lava at mid-ocean ridges record the magnetic field of the Earth at the time of their creation
• Magnetic stripes of normal and reversed polarity are parallel to mid-ocean ridges and symmetrical on both sides
• The magnetic stripes can be matched with records of geomagnetic reversals to determine the age of the seafloor
• Radioactive dating techniques are also used to determine the absolute age of the seafloor
• Magnetic reversals have happened many times in the past, and the records are preserved in the magnetized rocks of the ocean floor
• New seafloor is created at mid-ocean ridges and spreads out in both directions, creating a symmetrical "zebra-stripe" pattern of alternating normal and reversed polarity
• Ages of rocks


  • s
  • 2 years
  • 4 years
  • 8 years
• The Earth's lithosphere is divided into several plates and these plates ride over a weak asthenosphere
• Plates move away from each other (divergent), towards each other (convergent) and sliding past each other (transform)
• Convection current


  The circulation patterns that facilitate the movement of the plates
• Convection current


  1. Heat is produced in the core that produces convection in the mantle

  2. Convection causes the plate to move around
• The activity illustrates the circulation patterns known as convection current
• Convection current


  The plastic movement of the mantle material moves like the flow of mountain glaciers, carrying the lithospheric plates along as the convection movement in the mantle moves the asthenosphere