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

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Figure 3.2: <strong>The</strong> rock cycle, as <strong>we</strong> know it today.• Uplift - he had seen many examples where sedimentary, metamorphic and igneousrocks had been uplifted to form new land, exposing new ‘rocks at the Earth’s surface’.<strong>The</strong>se are shown on the rock cycle diagram, as <strong>we</strong> know it today, in Figure 3.2.But Hutton did even more than work out most of the rock cycle processes. He also realisedthat rock formation can be explained by the processes that <strong>we</strong> see working on Earth today.He discovered what was later called the ‘Principle of Uniformitarianism’ or ‘the present isthe key to the past’. He worked out that in the past, the Earth must have been subjectedto extremely high pressures, enough to uplift and tilt rocks, and very high temperatures,enough to melt rocks. His evidence also sho<strong>we</strong>d that the Earth must be very much olderthan most people thought. He wrote, ‘... <strong>we</strong> find no vestige of a beginning, - no prospectof an end’, meaning that there was no evidence preserved of how the Earth began, but itmust have been an awfully long time ago. <strong>The</strong>re was no evidence of how the world wouldend either - it would go on and on into the distant future. So <strong>we</strong> can add to Hutton’s rollof geological fame:• the ideas behind ‘the Principle of Uniformitarianism’;• ideas of the enormous pressures and temperatures that had affected the Earth inthe past;• realisation of the great age of the Earth, now called ‘geological time’ or ‘deeptime’.Hutton published all his ideas in a book called ‘<strong>The</strong>ory of the Earth’ in 1788, but althoughhis friends realised he was a great scientist, his genius as the ‘Founder of Modern Geology’was not recognised until many years later. Since then, his work has inspired generationsof geologists, including Charles Darwin.73
Figure 3.3: James Hutton, the ‘Founder of Modern Geology’.Although geologists through the 1800s and early 1900s knew that the Earth had beensubjected to great deformational processes in the past, and knew about the high temperaturesof magmas and metamorphic rocks, they didn’t know what had caused theseenormous pressures and temperatures. Lots of different ideas <strong>we</strong>re suggested, but noneof them seemed to give an ans<strong>we</strong>r that could explain geological events and their effectsacross the Earth. One idea put forward in the early 1900s by Alfred Wegener was the‘<strong>The</strong>ory of continental drift’, and this is his story and the story of what follo<strong>we</strong>d.3.2 Plate tectonics (20th Century)Alfred Wegener <strong>live</strong>d in Germany in the early 1900s at a time when most geologistsbelieved that the Earth’s crust was able to move up and down, but wasn’t able to movesideways. Wegener proposed in his ‘<strong>The</strong>ory of continental drift’ that the continentsdrifted across the Earth’s surface, forming mountain chains in mountain-building episodes.Wegener proposed his ‘big idea’ in 1912 and published the evidence for his idea in a series ofbooks until 1929. Meanwhile, as a polar explorer, he was leading expeditions to Greenlandand he died on the Greenland icecap in 1930 when he was 50 years old. Although he founda wide range of evidence to support his theory, his genius wasn’t recognised in his lifetime.It wasn’t until many years later that geologists realised that many of his ideas did explaina lot of the evidence.74
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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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Even diamond can have different col
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Figure 1.8: A red garnet crystal in
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Figure 1.12: Crystals of minerals i
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Hematite, Fe 2 O 3 - earthy red, me
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Figure 1.17: Sedimentary rocks show
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Figure 1.20: A close up view of a p
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Figure 1.26: Ancient wave ripple ma
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Figure 1.30: Coal seams in an openc
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Figure 1.32: Close up view of a pie
Page 37 and 38: Figure 1.35: A fossil colonial cora
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Page 45 and 46: Figure 1.44: A basalt flow that coo
Page 47 and 48: Figure 1.47: Deposit of volcanic as
Page 49 and 50: Figure 1.49: An old slate quarry, s
Page 51 and 52: Figure 1.51: Slate, a low-grade met
Page 53 and 54: Figure 1.53: Schist, a medium-grade
Page 55 and 56: Figure 1.56: Metaquartzite, produce
Page 57 and 58: Figure 1.58: A region of folded roc
Page 59 and 60: Figure 1.61: A normal fault. This s
Page 61 and 62: Figure 1.64: An unconformity. Older
Page 63 and 64: proper geological maps. Fossils hav
Page 65 and 66: Cephalopods are not extinct, but th
Page 67 and 68: Figure 1.68: A shelled cephalopod f
Page 69 and 70: You can try the rock sequencing pri
Page 71 and 72: Chapter 2Reading landscapes: how la
Page 73 and 74: Figure 2.3: Rock fragments loosened
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Page 79 and 80: are forming them. Similarly the sha
Page 81 and 82: Figure 2.19: This photo was taken f
Page 83 and 84: Figure 2.25: Dinosaur tracks conser
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Page 87: found evidence that the Earth was a
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Page 113 and 114: Figure 4.1: William Smith’s geolo
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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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