The planet we live on: The beginnings of the Earth Sciences

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Eon Era SystemNeogeneCenozoicPaleogeneCretaceousMesozoicJurassicAge, millions ofyears ago (Ma)02365146200PhanerozoicPrecambrianPalaeozoicProterozoicArchaeanHadeanTriassicPermianCarboniferousDevonianSilurianOrdovicianCambrian2512993594164444885422,5003,8004,600Figure 1.71: <strong>The</strong> geological time scale, used internationally55
Chapter 2Reading landscapes: how landscapescontain evidence of the relationshipbet<strong>we</strong>en past and present processesand the underlying geology2.1 <strong>The</strong> landscape is subject to processes of <strong>we</strong>athering,erosion and transportationAll the lumps and bumps you can see in the landscape, all the hills, valleys, ridges,mountains, lowlands, bays and headlands, are caused by just three things: the characterand structure of the underlying rocks, the type and po<strong>we</strong>r of the surface processes and,nowadays, human activity. This chapter will help you to stand on a hill and make senseof all the lumps and bumps in the landscape that you can see.In Figure 2.1 tough rocks form the hill the photo is taken from, the ridge in the distanceand the hills in the background, while <strong>we</strong>aker rocks underlie the plain below. <strong>The</strong> plain isflat because the <strong>we</strong>aker rocks underlying it <strong>we</strong>re eroded to a lo<strong>we</strong>r level before flat-lyingsediment was deposited on the top. Human activity has modified all this by buildingroads and buildings and excavating quarries, and by agricultural activity over thousandsof years.Weathering and erosion remove material from the higher places on Earth and it is transported,largely downhill, to the lo<strong>we</strong>r parts, where it is deposited. So higher points becomeworn down and sediment builds up in the lo<strong>we</strong>r parts. Weathering, erosion, transportationand deposition are therefore key elements of the sedimentary cycle.Weathering attacks all natural rock surfaces as <strong>we</strong>ll as all constructions, such as buildings,bridges and dams. Weathering is defined as: ‘the natural break up and break down ofrock and other materials at the Earth’s surface, without the removal of solid material’.‘Break up’ means that the material is broken into smaller pieces by physical processes,whilst ‘break down’ is chemical breakdown, into new compounds. During <strong>we</strong>athering,56
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Basic Books in ScienceBook 6<strong
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BASIC BOOKS IN SCIENCE- a Series of
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BASIC BOOKS IN SCIENCE- a Series of
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Looking ahead - If you came across
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3.2 Plate tectonics (20th Century)
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1.30 Coal seams in an opencast coal
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3.4 Alfred Wegener, the polar explo
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5.14 A GPS remote volcano monitorin
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Figure 1.2:minerals.A sandstone roc
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Page 55 and 56: Figure 1.56: Metaquartzite, produce
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Figure 4.12: The 4
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Millionsof years Some Major Earth E
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Figure 5.2: Strike-slip movement (r
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Figure 5.4: The So
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Figure 5.6: An ash eruption rising
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Figure 5.10: A hazard zone map of t
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isk to humans. The
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Figure 5.14: A GPS (global satellit
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None of these methods has yet prove
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Figure 5.17: A windfarm in Ireland.
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Figure 5.19: A beautifully preserve
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Another ‘missing link’ find has
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Figure 5.22: A dinosaur reconstruct
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Figure 5.25: A working aggregate-pr
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Figure 5.26: The E
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Chapter 6Understanding what geologi
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Figure 6.2: A drilling rig used for
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When an oil/gas field has been foun
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Figure 6.6: Groundwater flowing out
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Dam disaster in Italy, when the wav
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Figure 6.10: A slab foundation, bui
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An example of this is investigation
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GlossaryAbsolute age The</s
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Carbon capture The
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Crustal shortening This results of
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Evaporite deposits (or evaporites)
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Geophysical survey Using the method
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“Integrated waste management” <
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Metamorphism The r
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Pore spaces (or pores) Gaps bet<str
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Saltation Sediment movement by flui
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Suspension Sediment movement by flu
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AcknowledgementsPermission to repri
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Figure 2.3 A scree slope. Photo ID:
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Figure 1.15a Hematite.Figure 1.15b
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Figure 1.28 Dune cross bedding in s
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Figure 3.18 An island arc volcano,
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Figure 5.21 Excavations at the dino
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The planet we live on: The beginnings of the Earth Sciences

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