Slides for Leaving Certificate Geography on Rocks and their formation

2. Recapping from Junior Cert…
_____________ are formed from hot volcanic material that
has cooled down – two examples are __________ and
_______________.
________________ rocks are formed from particles of
animal or plant remains, or other rocks. Examples include
_______________ and ______________.
_________________ rocks are rocks that are changed by
great _____ or ___________. Examples include
____________ and _______________.

3. 2006 OL

4. Igneous rocks
 Formed underground (intrusive) or on the surface
(extrusive)
 Two basic intrusive types
 Plutonic – formed deep underground, with large crystals.
Example – Granite of Wicklow Mountains
 Hypabassal – formed close to the surface, smaller crystals.
Example – Dolerite of Co. Antrim.
 One extrusive type
 Basalt (Giant’s Causeway)

5. Hypabassal Dolerite – Fair Head sill
Formed close to the surface, has an
appearance like Basalt. Crystals are
small.

6. Plutonic Igneous Rock - Granite
Contains many crystals due to slow
cooling underground as it was
formed. Found in the Dublin &
Wicklow mountains (Batholith)

7. Extrusive Rocks - Basalt

8. Definitions & Examples
Extrusive ____________________________________________
Example of Extrusive rock ______________________________
Intrusive ____________________________________________
Hypabassal __________________________________________
Example of Hypabassal Rock ____________________________
Plutonic _____________________________________________
Example of Plutonic Rock _______________________________

9. 2010 HL

10. 2010 OL

11. 2010 Ordinary Level LC

13. Sedimentary rock - formation
 Key words and phrases
 Accumulation – build up of Strata (layers) of particles
 Compaction – squashing of layers together
 Cementation – glueing together of particles
 Lithification – the process of changing sedimentation into
stone

14. Sedimentary Rock types
 Organically formed from dead plant/animal material (e.g.
Coal, Limestone, Chalk)
 Inorganically formed – from particles of other rocks (e.g.
Sandstone, Mudstone)
 Chemically formed (less common) – formed from
evaporation of sea water, leaving the salts behind (e.g.
Gypsum, Rocksalt)

15. Gypsum – a chemically formed sedimentary
rock (from seawater evaporating)

16. Sediments laid down – a salt pan

17. Metamorphic Rocks – P 68
 Three types:
 Thermal (rocks changed by intense heat – e.g. Quartzite
(thermal metamorphism of Sandstone, Sugar Loaf
Mountain)
 Dynamic Metamorphism – (rocks changed by pressure –
e.g. Shale into slate)
 Regional Metamorphism – (rocks changed over a long time
and over a large area, being slowly “cooked” to form new
rocks e.g. Gneiss. Found in N. Scotland, NW Ireland and
Canada)

19. Metamorphic Rock - Gneiss

20. Slate used as a roofing material

21. Ireland’s Rocks

22. 2011 LC Hons Q

23. Rock Cycle – P 62
 http://www.youtube.com/watch?v=U7YQ5vwaL98
 The process by which rocks are constantly “recycled” by
the natural processes of the Earth.

25. The Rock Cycle

26. 2006 LC HL

27. Tara Mines – Case Study

28. Case Study - Tara Zinc and Lead
mines
 An important Primary Economic Activity in the GDA (Greater
Dublin Area)
 At Tara Mines people interact with the Rock Cycle in many
different ways
 Constructing Shaft Mines
 Working on new methods to extract ore
 Inventing safe methods to dispose of mining waste
 Developing transport systems to move ore to the market

29. Zinc and Lead

30. Zinc and Lead - uses
 Zinc
 Used in alloys for car manufacture
 Galvanising
 Dietary supplements
 Batteries
 Lead
 Soldering
 Bullets
 Batteries

31. Shaft Mine

32. Tara Mines – ore extraction

33. Tara Mines – stope and pillar
mining

34. Ore Transportation

35. Tara Mines
 Largest Zinc Mine in Europe, 5th largest in the world
 Ore (rock that contains the metals) is extracted at Navan,
shipped to refineries in Finland and Norway
 The ore was formed approx 350 million years ago between
layers of carboniferous limestone, now lies 500 to 900m below
surface
 “Stope and Pillar” mining is used (see p 66)
 Rock is crushed to a powder, mixed with water and chemicals
to remove the metals from the rock
 Waste water is toxic, needs to be treated carefully

37. Tara Mines - Environment
 Mining is potentially very dangerous for environment
 Sediments and chemicals used are vulnerable to transport
by wind – can get blown onto crops, towns, people
 Since 1997 improvements have been made at the mine to
improve the local environment
 Waste water treated by natural bacteria
 Landscaping in local area
 Restoration of tailings pond (where sediments are allowed
to settle)
 Constant monitoring for pollution

38. LC Exam Question on mining
(2009)
 Discuss, with reference to one of the following, how humans
interact with the rock cycle (30 marks)
 Mining
 Extraction of building materials
 Oil / Gas exploitation
 Geothermal energy production
Marking Scheme
 Interaction identified: 2 marks
 Discussion: 14 x SRPs
 Give credit for up to two examples of location.

39. LC Exam Question 2009
Examine, with reference to examples from Ireland, the
formation of sedimentary rocks. [30m]
Marking Scheme
 Name two sedimentary rocks: 2 + 2 marks
 Name two associated Irish locations: 2 + 2 marks
 Examination: 11 x SRPs
 Give credit for 1 SRP for diagram without annotation.
 Give credit for extra labelling in diagram from Examination
SRPs.
 Allow treatment of up to 3 rocks in examination.
 At least 3 SRPs for treatment of second sedimentary rock
 If description only –2 x SRPs max