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

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Chapter 4Major geological events fit into atimeline, beginning with theformation of the Earth4.1 <strong>The</strong> origin and development of lifeWilliam Smith was a canal engineer who supervised the excavation of boat canals acrossEngland in the late 1700s and early 1800s. When cuttings for the canals had to be madethrough hilly areas, he noticed that the layers of sedimentary rock always formed the samesequence. He also noted that the same layers always contained the same fossils and thatthe sequence of fossils was always the same. He called this his ‘Law of Faunal Succession’and this helped him to link together rocks from different parts of the country because theycontained the same fossils. This is a method <strong>we</strong> now call correlation. By correlating rocksequences across the country, Smith was able to produce a geological map of England andWales (shown in Figure 4.1), the first geological map of a country ever produced (althoughgeological maps of smaller areas had previously been made in Europe).Smith knew that fossils occurred in a certain sequence in rocks - but he didn’t knowwhy. In fact most people at that time (with the exception of a few scientists) didn’t evenquestion the meaning of the fossils in rocks, believing that all rocks had been formed,with fossils inside some of them, during creation a few thousand years before. It wasn’tuntil Charles Darwin proposed his theory of evolution by natural selection that a reasonfor the sequence of fossils in the rock was provided. Darwin published his book, ‘On theorigin of species by natural selection’ in 1859, basing it on his reading of other scientificpublications and a mass of geological and biological evidence he had collected himself.He realised that when plants and animals reproduce, they produce new young organisms,some of which are better adapted to the environment than others. Through ‘naturalselection’ the best adapted ones survive and the less <strong>we</strong>ll adapted ones die. This meansthat slightly different, better-adapted organisms develop and, if this continues, wholenew types of organisms can form as one species develops into another through evolution.This explains why different rocks contained the different fossils that William Smith had97
Figure 4.1: William Smith’s geological map of England and Wales, published in 1815,made using his ‘Law of Faunal Succession’.98
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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
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Figure 1.35: A fossil colonial cora
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Figure 1.38: Fossil ammonites, indi
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Figure 1.39: ‘Massive’ igneous
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Figure 1.41: A close up view of a p
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Figure 1.44: A basalt flow that coo
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Figure 1.47: Deposit of volcanic as
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Figure 1.49: An old slate quarry, s
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Figure 1.51: Slate, a low-grade met
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Figure 1.53: Schist, a medium-grade
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Figure 1.56: Metaquartzite, produce
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Figure 1.58: A region of folded roc
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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
Page 75 and 76: Figure 2.6: The jo
Page 77 and 78: Figure 2.10: The m
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 and 88: found evidence that the Earth was a
Page 89 and 90: Figure 3.3: James Hutton, the ‘Fo
Page 91 and 92: Figure 3.5: A page of Wegener’s 1
Page 93 and 94: Figure 3.7: The st
Page 95 and 96: Figure 3.10: The r
Page 97 and 98: Figure 3.13: The m
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Page 101 and 102: Figure 3.19: An ocean versus contin
Page 103 and 104: Figure 3.23: Map of the major tecto
Page 105 and 106: Figure 3.26: Global temperature cha
Page 107 and 108: Figure 3.29: A computer generated p
Page 109 and 110: Figure 3.31: The
Page 111: planet extended th
Page 115 and 116: Millionsof yearsago (Ma)01000Some M
Page 117 and 118: ocks whilst the first definite plan
Page 119 and 120: Figure 4.9: The ch
Page 121 and 122: Figure 4.12: The 4
Page 123 and 124: Millionsof years Some Major Earth E
Page 125 and 126: Figure 5.2: Strike-slip movement (r
Page 127 and 128: Figure 5.4: The So
Page 129 and 130: Figure 5.6: An ash eruption rising
Page 131 and 132: Figure 5.10: A hazard zone map of t
Page 133 and 134: isk to humans. The
Page 135 and 136: Figure 5.14: A GPS (global satellit
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Page 139 and 140: Figure 5.17: A windfarm in Ireland.
Page 141 and 142: Figure 5.19: A beautifully preserve
Page 143 and 144: Another ‘missing link’ find has
Page 145 and 146: Figure 5.22: A dinosaur reconstruct
Page 147 and 148: Figure 5.25: A working aggregate-pr
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Page 151 and 152: Chapter 6Understanding what geologi
Page 153 and 154: Figure 6.2: A drilling rig used for
Page 155 and 156: When an oil/gas field has been foun
Page 157 and 158: Figure 6.6: Groundwater flowing out
Page 159 and 160: Dam disaster in Italy, when the wav
Page 161 and 162: 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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