Knowledge and understanding Geological techniques and skills Comments Minerals are formed by: crystallisation from a melt [quartz, feldspar, mica, olivine and augite] metamorphic [calcite, garnet] crystallisation from solution in evaporating water [halite] crystallisation as cement from flowing pore waters [quartz, calcite] crystallisation from hydrothermal fluids [in veins and faults: gangue minerals – quartz, calcite; ore minerals – haematite, galena]. Use appropriate tests of: physical properties of minerals [observation of colour, streak, cleavage, lustre] [reaction with 0.5 mol dm−3 hydrochloric acid] to identify and distinguish between the minerals on the data sheet. Interpret data from the data sheet. Equipment to be used includes a streak plate, hand lens, 0.5 mol dm−3 hydrochloric acid, fingernail, copper coin, steel pin and a mineral data sheet. See Practical Guidance Sheet 1. See Practical Guidance Sheet 2. Candidates are not required to memorise information on the data sheet, which will be provided in the assessments. b. Modern laboratory techniques can be used to image mineral samples on a small scale and determine their chemistry e.g. the scanning electron microscope and electron microprobe. N.B. Access to these techniques is not required. Candidates should be made aware of the laboratory techniques and equipment used to image and identify minerals at a microscopic level. Knowledge of the workings of the instruments and the methods of sample preparation is not required. hardness
Knowledge and understanding Geological techniques and skills Comments a. Igneous rocks have diagnostic properties; colour and texture [crystal size, equicrystalline, porphyritic and orientation]. Identify the named igneous rocks in hand specimens/rock exposures, diagrams and photomicrographs from observation of their colour, crystal size [coarse >3 mm, fine <1mm], random crystal orientation of phenocrysts/groundmass and mineralogy. See Practical Guidance Sheet 4. See Practical Guidance Sheet 5. Igneous rocks [peridotite, basalt, andesite, granite] can be classified by: texture mineralogy. Candidates should be able to distinguish between peridotite, basalt, andesite and granite in hand specimens, photomicrographs and photographs on the basis of crystal size and mineralogy. c. Crystal size in igneous rocks is related to the cooling rate of magma. Candidates should be able to interpret the cooling history of igneous rocks from measurements of crystal size including porphyritic in hand specimens, photomicrographs or diagrams. Interpretation to include two stage cooling in addition to slow, moderate or rapid cooling rates.
Knowledge and understanding Geological techniques and skills Comments d. Magma viscosity affects the type of volcanic activity and the shape of volcanoes – the differences between relatively passive [fissure] and violent eruptions [central vent]. Recognise and interpret the differing shapes of volcanoes from diagrams/photographs. Investigate factors affecting the length of lava flows using the ‘Jelly lava flow’ simulation experiment or equivalent. Factors investigated to include viscosity (related to temperature) and slope angle. Candidates should be able to distinguish between shield volcanoes and composite cones based on their size, shape and composition. Kilauea/Mauna Loa v Mount Pinatubo/Mount St. Helens. Practical activity using a rigid smooth surface at a range of angles with materials of different viscosities being timed to flow down it. Materials could include jelly. Materials could be tested from the fridge, at room temperature and after heating to a predetermined temperature. See Practical Guidance Sheet 3.
Knowledge and understanding Geological techniques and skills Comments Igneous bodies can be distinguished by: structure [columnar jointing, pillow lava] form [lava flows, sills, dykes and plutons] field relationships. Identify the characteristics of igneous bodies [crystal size, structures, field relationships] as seen in hand specimen/rock exposures, diagrams and photographs. Analyse simplified geological maps and cross-sections to interpret their contrasting modes of formation. Candidates should have the opportunity to make annotated sketches of these features from photographs or field outcrops. Candidates should be able to distinguish between baked and chilled margins, metamorphic aureoles and discordant and concordant relationships with the country rocks. Candidates should be able to distinguish between lava flows and sills on the basis of field evidence; baked margins, vesicles, xenoliths, crystal size, weathered upper surfaces.
Knowledge and understanding Geological techniques and skills Comments f. Distinctive sedimentary structures [lamination/bedding, cross bedding, graded bedding, ripple marks, desiccation cracks] are characteristic of their environments of deposition. Fossils are indicators of past environments: reef-building corals [marine, shallow, warm] trilobite [marine], ammonite [marine] plants [terrestrial, indicating past climate] trace fossils [tracks indicating terrestrial, burrows indicating shallow water]. Identify the following fossil groups on the basis of their morphology [trilobite, ammonite, coral, plants, trace fossils – burrows, footprints], as seen in hand specimens, diagrams/photographs. The following morphological features should be recognized in these fossil groups: Corals; septa. Trilobites; cephalon, thorax, pygidium, eye. Ammonites; suture line. Plants; leaf, stem, root. Trace Fossils; footprints, burrows.
Knowledge and understanding Geological techniques and skills Comments a. Metamorphic rocks are the result of increased temperature and/or pressure on pre- existing rocks causing recrystallisation to form new minerals and textures. Identify the named metamorphic rocks in hand specimens from observation of their crystal size [coarse, fine], crystal orientation [aligned, random] and reaction with 0.5 mol dm−3 hydrochloric acid. See Practical Guidance Sheet 4. Metamorphic rocks [slate, schist, marble, metaquartzite] have diagnostic textures [crystal size and orientation]: non-foliated texture foliated texture [slaty cleavage and schistosity]. Identify the characteristic features of a metamorphic aureole on diagrams and simplified geological maps and cross-sections. Candidates should know the cause of contact and regional metamorphism. Candidates should be aware that some of the stated rocks can be the product of both contact and regional metamorphism. c. Metamorphic rocks [schist, marble and metaquartzite] have diagnostic mineralogy. Use the characteristics of metamorphic rocks [texture, mineralogy, acid reaction] as seen in hand specimens/rock exposures, diagrams and photographs, simplified geological maps and cross-sections to interpret their contrasting modes of formation [contact and regional metamorphism]. See Practical Guidance Sheet 4. See Practical Guidance Sheet 5.
Knowledge and understanding Geological techniques and skills Comments a. The rock record provides evidence of tectonic activity. Describe safety precautions to be taken when visiting field exposures. Measure strike and dip. Analyse strike and dip measurements to describe and interpret rock structures in 3D. Candidates should be aware of the importance of a range of safety precautions when visiting field locations (including coastal locations). See Practical Guidance Sheet 9. Candidates should be able to interpret dip and strike data to interpret rock structures in 2D (maps and cross sections) and 3D (block diagrams). b. Folding is caused by tectonic stress [compressional]. Interpret characteristic features of folding in field exposures, diagrams, photographs, simplified geological maps and cross- sections: horizontal beds dipping beds folded beds [antiform, synform, axial plane trace, limb]. Candidates will not be required to distinguish between the terms antiform/anticline synform/syncline.
Knowledge and understanding Geological techniques and skills Comments c. Faulting is caused by tectonic stress [compressional, tensional, shear]. Interpret features of rock deformation by faulting in field exposures, diagrams, photographs, simplified geological maps and cross sections: normal fault reverse/thrust fault strike-slip fault fault displacement. Candidates should be able to measure the amount of fault displacement using an appropriate scale from a map or cross section. d. Unconformities are gaps in the rock record. Angular unconformities are formed by a sequence of events including deformation, uplift, erosion and later deposition. Identify unconformities in the field, in diagrams, photographs, geological maps and cross-sections. Use unconformities in interpreting the geological history of exposures.
Knowledge and understanding Geological techniques and skills Comments a. Sedimentary, metamorphic and igneous processes and rocks are linked by the rock cycle [energy transfer] over geological time. Interpret rock cycle diagrams. Candidates should be aware that the sedimentary processes of the rock cycle are controlled by the hydrological cycle. Igneous and metamorphic processes are controlled by plate tectonics. Candidates should be aware of the importance of gravity in order for the rock cycle to operate. b. Rock cycle processes take place at different rates, from seconds to millions of years [catastrophism v gradualism – e.g. meteorite impact v river erosion]. Distinguish between processes reflected in the rock record that occurred at different rates. Candidates should be able to order geological events in terms of their duration from a given list for example meteorite impact, earthquake, landslide, volcanic eruption, formation of an ocean, formation of a mountain range.
Knowledge and understanding Geological and skills Comments The Earth has a concentric structure based on its: chemical properties [crust, mantle and core] mechanical behaviour [lithosphere, Candidates should be able to appreciate the relative thicknesses of the different layers of the Earth. Teachers are referred to the following practical demonstrations: 1. Using a toilet roll to demonstrate the variation in thickness of the Earth’s layers (crust, mantle, lithosphere and core). b. The mechanical behaviour of the outer Earth involves the lithosphere [cold, rigid outer shell composed of crust and uppermost mantle]. It is underlain by the asthenosphere [weaker layer composed of upper mantle]. 2. Bending two chocolate bars, one of which has previously been frozen, to demonstrate the effect of temperature on brittle and plastic deformation of the same material. c. The lithosphere is divided into a number of rigid ‘tectonic plates’ which move relative to one another by mechanisms not yet completely understood. Candidates should be aware of the possible causes of plate movement (slab pull and ridge push).
Knowledge and understanding Geological techniques and skills Comments g. Plate theory is being continually re-evaluated in the light of new evidence e.g. seismic tomography and ocean drilling – RRS James Cook, Joides Resolution 360 (2016). Candidates should be aware of the latest advances in plate tectonic theory by using internet based resources. seismic tomography is providing evidence of asymmetric spreading at the Mid Atlantic Ridge deep ocean drilling is leading to a of the base of the ocean crust.
Knowledge and understanding Geological techniques and skills Comments Geological events are dated and interpreted using stratigraphic principles: uniformitarianism – the present is the key to the past the concepts of original horizontality, lateral continuity and superposition of strata the relative dating of rocks on the basis of included fragments, cross cutting relationships. Investigate the link between ancient and modern processes by applying the principle of uniformitarianism. Apply the principles of relative dating to interpret the evidence in rock exposures in the field, in diagrams/photographs and simplified maps and cross- sections for the sequence of geological events that formed/deformed them. b. Rocks can be dated and correlated using the evolutionary change of zone fossils over time. Candidates should be aware that graptolites are used to zone the Lower Palaeozoic and cephalopods can be used to zone the Upper Palaeozoic and Mesozoic. The following zone fossil groups have morphological changes with time that are used in dating/correlation: cephalopods [goniatites, ceratites, ammonites – suture line] graptolites [stipes, thecae]. Use the named fossils, as seen in specimens and diagrams/photographs to interpret the geological history of a rock sequence.
Knowledge and understanding Geological techniques and skills Comments d. The decay of radioactive materials provides a method of absolute dating for some rocks and minerals. Carry out a simple analysis of the age of a radioactive mineral based on the half-life concept [parent - daughter ratio, unstable parent, stable daughter]. e. The development of the concept of Deep Time [Ussher (The Bible), Hutton, Kelvin, Joly and Holmes] has extended the age of the Earth back to around 4.6 billion years. Candidates should be aware of the different methods that have been used to attempt to find the age of the Earth during historical times.
Knowledge and understanding Geological techniques and skills Comments g. Global warming/ cooling affects continental ice sheet dimensions and global sea level. Investigate the evidence from the internet, maps and aerial images for past and current fluctuations in continental ice and the effect on global sea levels. h. Carbon is a geological strategy for reducing atmospheric carbon dioxide. Candidates should be aware of the potential of depleted oil and gas reservoirs as being suitable sites for carbon sequestration.
Knowledge and understanding Geological techniques and skills Comments Major fossil finds show: rare and exceptional preservation [Burgess shale fauna] the links in macro fossil evolution through the morphology of modern reptiles and birds [Archaeopteryx] that complex fossil skeletons have to be interpreted from incomplete and disarticulated remains [dinosaurs] features of early hominids [“Lucy”]. Evaluate the significance of the incomplete nature of the fossil record. Candidates should be aware that the fossil record is biased and over represented by marine organisms that had shells. Candidates should be aware that many reconstructions of extinct organisms, particularly dinosaurs, are often based on just a few bones. Candidates should be aware that hominid fossils are exceptionally rare and only a few quality specimens of early hominids exist e.g. Lucy. Important features include bipedal gait and enlarged brain case of skull.
Knowledge and understanding Geological techniques and skills Comments There is a distinction between Earth’s: resources – naturally occurring useful substances reserves of a resource – the calculated amount that is economic to extract. b. Mineral resources are important in construction, industrial manufacturing and energy generation. Investigate the uses of the following minerals [Limestone for aggregate in construction Haematite in the steel industry Uranium in energy generation]. Candidates should be aware of how the physical and chemical properties of these three geological materials influence their use. Geologists prospecting for new reserves use a variety of techniques: geological mapping borehole correlation [using microfossils] geophysical [seismic, magnetic and ground penetrating radar] geochemical [soil and river sediment analysis]. Interpret prospecting data [geological mapping, geophysical, geochemical] to identify possible valuable mineral resources. Candidates should be able to decide which prospecting technique(s) is/are the most appropriate for locating different types of geological materials (e.g. oil and gas, metalliferous minerals).
Knowledge and understanding Geological techniques and skills Comments e. There are technological difficulties and environmental issues involved in exploring for and extracting oil and natural gas [including fracking]. Candidates should have studied a range of case studies such as Blackpool/USA (fracking) and Gulf of Mexico (oil leak) but they will not be required to recall specific case study detail in assessments. Factors affecting the extraction of underground water from aquifers include: height of the water table porosity/ permeability of the aquifer the presence of natural springs the distribution of wells. Analyse different rock types for their suitability as an aquifer. Candidates should have studied a range of case studies such as Nottingham (desert sandstone) and London (chalk) but they will not be required to recall specific case study detail in assessments. The impact of domestic and hazardous waste disposal on vulnerable aquifers depends upon: geological factors engineering factors monitoring of potentially polluted water restoration of contaminated ground. Use data from descriptions, diagrams/photographs, maps and to: investigate the suitability of a potential landfill site for the disposal of domestic waste. investigate the suitability of a potential site for the long term storage of hazardous waste. Candidates should have studied a range of case studies such as Sellafield and the Arthurstown landfill site, but they will not be required to recall specific case study detail in assessments. sections cross-