Geological landscapes

Question 1

What type of stone is commonly found in Sydney?

Answer 1

• The geology of the Sydney area is dominated by sandstone which formed between 200 and 300 million years ago (Triassic to Permian)
• Some contain fossils, mostly of plants from the age of the Dinosaurs

Question 2

What is the Law of Superposition?

Answer 2

• Sedimentary rocks are deposited into layers/strata and the older strata are at the bottom while the younger strata are at the top.
• The age of sedimentary rocks can be determined by their relative position or stratigraphy

Question 3

What is Stratigraphy?

Answer 3

• The branch of geology concerned with the order and relative position of strata and their relationship to the geological timescale

Question 4

Why is the Law of Superposition useful?

Answer 4

• It is a useful tool in deciphering geological history – in combination with absolute dating methods like geoclocks

Question 5

What is a craton?

Answer 5

• A craton is a part of continental crust that is at least 1 billion years old and unaffected by tectonic activity
• For example, The Pilbara is a geological feature known as a ‘craton’. Dating of zircon crystals indicates the Pilbara is about 3.5 billion years old

Question 6

What were the first two key concepts for this lecture?

Answer 6

• Geological landscapes are varied and can be interpreted based on rock features and predominant mineral groups
• The east coast of Australia experienced volcanism between 100 and 10 million years ago as the continent migrated over a hotspot

Question 7

What were the last two key concepts for this lecture?

Answer 7

• Sedimentary landscapes exhibit strata, or layers, of rock sequences which are deposited in a time sequence with older strata at the bottom and younger strata on top = Law of Superposition
• Cratons are very old (> 1 billion years) and stable parts of continental crust, dominated by the rock type granite