Paper1 Darwin

KUWAI T Paper 1 The Geological Journey of Charles Darwin Charles Darwin was a modern naturalist ‫ عالم طبيعة معاصر‬wi...

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Paper 1

The Geological Journey of Charles Darwin

Charles Darwin was a modern naturalist ‫ عالم طبيعة معاصر‬with a passion ‫ شغف‬for Geology, even if most people would think of him as a biologist ‫ عالم أحياء‬. He believed in the words of Alexander von Humboldt: “It is by isolating facts that travellers ‫ عزل الحقائق‬have given birth to so many false ideas ‫عزل الحقائق الغائبة جزئيا يتيح الفرصة لوالدة‬ ‫)…( أفكار خاطئة‬. The great geological phenomena are subject to the same laws ‫الظواهر الجيولوجية الكبيرة تخضع لنفس‬ ‫القوانين‬, as well as the forms ‫ تكوين‬of plants and animals”. He studied with some of the first scientific geologists ‫أوائل الجيولوجيين‬, like John Stevens Henslow, Adam Sedwick (the Geology Museum of Cambridge University is devoted to this man that took Darwin to his fieldtrips ‫ )الرحالت الحقلية‬and Charles Lyell (who insisted ‫ أصر‬upon Darwin the importance and urgency of publishing ‫ الحاح النشر‬his Origin of Species). In fact, the only paid job in Darwin’s life was the position of Secretary of the Geological Society of London. ‫(كلف متحف الجيولوجيا من جامعة كامبريدج أخذ داروين إلى الرحالت الميدانية‬ ‫ في الحقيقة العمل الوحيد مدفوع األجر لداروين كان‬.)‫وأيضا تشارلز ليل (الذي أصر على داروين وبإلحاح أهمية نشر كتابه أصل األنواع‬ . ‫سكرتير الجمعية الجيولوجية في لندن‬ The offer of Captain Fitzroy to travel with him, onboard HMS Beagle, gave Darwin an opportunity to explore the Earth. When Darwin chose a little bunch of books for his luggage, he took Lyell’s Principles of Geology where he read: “A sketch of the progress of Geology is the history of a constant and violent struggle between new opinions and ancient doctrines…” When the Beagle set sail from Davenport on 27 December 1831, he wanted to play a role on this history. Moreover, when he arrived to Falmouth 2 October 1836, almost five years later, he had done even more: his contributions to Geology, being important, where to be shadowed by his contributions to Biology. ‫ عندما اختار داروين حفنة‬.‫ أعطى داروين فرصة الستكشاف األرض‬،‫ على متن سفينتى بيغل‬،‫العرض المقدم من الكابتن فيتزروي للسفر معه‬ :‫ أخذ كتاب (مبادئ الجيولوجيا ) للكاتب لييل حيث قرأ‬،‫صغيرة من الكتب ضمن أمتعته‬ "... ‫"رسم تخطيطي للتقدم المحرز في الجيولوجيا في م تاريخ الصراع المستمر والعنيف بين اآلراء الجديدة والمذاهب القديمة‬ ،‫ وعالوة على ذلك‬.‫ كان يريد أن يلعب دورا في هذا التاريخ‬،1381 ‫ كانون األول عام‬72 ‫عندما أبحر بيجل من دافنبورت في‬ ، ‫ ما قام به كان أكثر من ذلك حيث أن أهمية اسهاماته في علم الجيولوجيا‬،‫ وبعد خمس سنوات تقريبا‬،1381 ‫ أكتوبر‬7 ‫عندما وصل إلى فالموث‬ .‫تتركز في كونها تحت مظلة إسهاماته في البيولوجيا‬

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 1

Figure1.Voyage of the Beagle. Key : 1 Plymouth - 2 Tenerife - 3 Cape Verde - 4 Bahia - 5 Rio de Janeiro - 6 Montevideo - 7 Falkland Islands - 8 Valparaiso - 9 Callao / Lima - 10 Galapagos - 11 Tahiti - 12 New Zealand - 13 Sydney - 14 Hobart - 15 King Sound – 16 Cocos (Keeling) Islands - 17 Mauritius - 18 Cape Town - 19 Bahia - 20 Azores During the Beagle expedition ) ‫( بعثة استكشافية‬, Darwin made many important geological observations and interpretations –some still accepted )‫(بعض المشاهدات والتفسيرات بعضها ال زال مقبوال‬. However, he also passed across geological phenomena impossible to understand with the knowledge and tools of the day. Therefore, following Charles Darwin and the Beagle is still a trip of geological exploration. .‫إطلع على نظريات جيولوجية كانت من الصعب فهمها باستخدام األدوات و المعرفة المتاحة غي ذلك الوقت‬ 1. The Beagle main target was mapping. To take precise measures it carries some 28 precision chronographs (the best then manufactured). Watches were essential (and still are useful) to measure… ‫ أداة قياس وقت دقيقة ( التي تم تصنيع األفضل منها‬82 ‫كان هدف العال م بيجل هو تصميم خرائط بأخذ قراءات وقياسات دقيقة والتي استخدم معها‬ :‫الحقا ) كانت الساعات أكثر أهمية وال تزال مستخدمة للقياس‬ a) Navigation distance ‫المسافة المالحية‬ e) Coastal drift ‫الجرف الساحلي‬ b) Geographic Latitude ‫خطوط العرض‬ f) Sea Altitude ‫ارتفاع البحر‬ c) Geographic Longitude ‫خطوط الطول‬ g) Relative Humidity ‫الرطوبة النسبية‬ d) Tide amplitude ‫السعة الموجية‬ h) Atmospheric pressure ‫الضغط الجوي‬ 2. Mark ALL the tectonic plates that the Beagle crossed in its route ‫…مساره‬ ‫حدد كل الصفائح التي مر بها العالم بيجل‬ a) African e) Australian b) Antarctic f) Cocos c) Arabian g) Eurasian d) Atlantic h) Indian

i) j) k) l)

Nazca North-American Pacific South-American

3. Between the voyages ‫ الرحالت‬of Christopher Columbus ‫( العالم كريستوفر كولومبس‬1492-1493) and Charles Darwin ‫( والعالم داروين‬1831-1832) had passed some 350 years. Assuming ‫ بافتراض‬that tectonic activity ‫النشاط‬ ‫ التكتوني‬has remained constant ‫ظلت ثابتة‬, Darwin found ‫ داروين اكتشف‬an Atlantic Ocean approximately… a) 300 m wider ‫أوسع‬ e) 10 m narrower ‫ضيق‬ b) 100 m wider f) 100 m narrower c) 10 m wider g) 300 m narrower h) Impossible to know even today d) Equal in width ‫متساويين في العرض‬

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 2



Modern ocean navigation gets important information from meteorological agencies ‫أجهزة المالحة البحرية تحصل على‬ ‫معلومات من وكاالت األرصاد‬ ‫ الجوية‬and models. For instance, ‫ على سبيل المثال‬many institutions ‫ العديد من المؤسسات‬, using different physical and mathematical models, predict ‫ تتنبأ‬the trajectory of hurricanes ‫ مسار األعاصير‬. A common way to ensemble the diversity of predictions is a Spaghetti Plot (figure 2). ‫الطريقة التي يتم فيها توصيل النقاط‬ )‫على شكل خطوط ( تشبه السباغيتي‬ Each individual forecasts is represented by one line, and merged into one image.

Figure2. Spaghetti plot for tropical storm Irene, August 2011 4. The purpose ‫ الغرض‬of a spaghetti plot is to give the user some idea of the… a) b) c) d) e)

Width of the hurricane ‫عرض األعاصير‬ Reliability of the prediction‫واقعية التنبؤات‬ Straightness of trajectories ‫االستقامة في المسارات‬ Time of arrival of hurricanes ‫وقت وصول األعاصير‬ Area affected by hurricane ‫المناطق المتأثرة باألعاصير‬

5. Which of the three areas marked in figure 2 provides the shortest term prediction ‫توفر تنبؤات قصيرة المدى‬ within this diagram a) A c) C b) B d) None After a visit to Cape Verde Islands , the Beagle sailed ‫ أبحر‬across the Atlantic Ocean and that Cape Verde included the visit to St. Paul’s Rocks (figure 3). St.Paul’s Rocks (Brazil) is uninhabited ‫غير مأهولة‬ set or rocky islets ) ‫ ( جزر صخرية‬in the Atlantic St Paul Rocks, Brazil Ocean, very close to the equator ‫خط االستواء‬ (00º55' N 29º20). The Beagle docked ) ‫( رست‬on Fernando de Norohna, the islets ‫ الجزر‬on 16 February 1832 and Darwin Brazil set to explore a place that was to challenge his geological knowledge ) ‫( تحدي المعلومات الجيولوجية‬. Salvador de Bahia, Darwin wrote “Is not this the first Island in the Brazil Atlantic which has been shown not to be of volcanic origin?” ‫ أصل بركاني‬and “unlike anything Figure 3. The route of the Beagle across the Atlantic Ocean, with which I have met with”. Late in 20th century the indication of the islands that Darwin could explore. samples that Darwin had taken in the spot ) ‫( بقعة‬ IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 3

where identified as “mylonited ‫ معدن الميلونيت‬amphibole-rich peridotites) ‫”( صخر البريدوتيت‬. Mylonites were defined in the 1880s, peridotites in the 1840s and plate tectonics did not arrive until the 20th century. Hence, we can feel like the astonished Darwin ) ‫( دهشة داروين‬. 6. According with General Atmosphere Circulation models, which wind direction ‫ اتجاه الريح‬should dominate in St. Pauls Rocks? a) Northward c) Southward b) Eastward d) Westward 7. Given the composition ‫ تركيب‬of a peridotite ‫بيروديتيت‬, an igneous rock rich in olivine, and given the setting of St. Paul’s Rocks, the most likely origin ‫ أصله‬of them must be a fragment ‫ قطع‬of… a) South-America or Africa continental lithosphere , trapped ‫ محاصر‬during the first phases ‫ مراحل‬of splitting ‫انقسام‬. b) Some old subduction zone ‫ منطقة االندساس القديمة‬in the Atlantic coast, when the ocean was narrower. c) Mantle brought ‫ انبثاق الوشاح‬to the surface during the splitting of Africa and America. d) The Earth’s outer core ‫ اللب الخارجي‬brought to the surface by deep convection ‫تيارات الحمل العميقة‬. 8. Mylonites are metamorphic rocks produced by friction ‫ احتكاك‬and pressure. These rocks can be related ‫يعود إلى‬ to… a) Ocean ridge volcanism ‫تبركن الحيد المحيطي‬ c) Subduction friction ‫االحتكاك الناشئ عن‬ ‫االندساس‬ b) Transform fault movement ‫حركة الصدع‬ d) A triple point between three plates ‫النقطة‬ ‫المماسية‬ ‫الثالثية بين ثالثة الواح‬ On 22 August 1832, the Beagle was sailing from Montevideo to Bahia, North of Cape St Antonio (approx. 36º S 56º W). 9. Given the Earth radius ‫ قطر األرض‬is 6371 km and the sky was very similar to present, how far should the Beagle travel to see both  Ursae Polaris ‫( النجم القطبي‬the Northern Star) and  Octantis (very close to the Southern Cross)? a) 6371 km northwards e) 4000 km eastwards b) 4000 km northwards f) 2000 km southwards c) 2000 km northwards g) 4000 km southwards d) 6371 km westwards h) 6371 km southwards The Beagle arrived Ygn ‫ وصل‬in Buenos Aires (Argentina) 311 days after its departure ‫ مغادرته‬from Britain, on 2 Nov 1832. Until January 1833, Darwin had countless occasions ‫ مناسبات ال تعد وال تحصى‬to explore the Atlantic Argentina coast, the Pampa and the Patagonian regions. This rather flat area, covered by loess ‫رواسب اللوس‬, hides a complex geologic history and structure. Study the following idealized profile and answer the following questions (figure 4).

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 4

1 2 3 A Parent Atoms %

4 5 6




8 9



100 150 200 Time in millions of years (Ma)


Figure 4. LEFT: Schematic section of the geological units in a region of the Atlantic Coast of South America. Key: 1. Loess. 2. Igneous rock with concentration of [xxGx]=70% of original. 3. Sandstone with rodents teeth and contact metamorphism on top.4. Nummulithic Limestone. 5. Late Mesozoic Clay with Ammonites. 6. Limestone. 7. Folded Schist. 8. Granite ([ xxGx]=4.42% of original). 9. Aplite ([xxGx]=6.25% of original). A, B and C. Disconformities. RIGHT: Blank disintegration diagram for isotope xxGx . 10. Loess is a deposit that covers huge extensions ‫امتدادات عظمى‬ the wind but it’s produced from…

of Patagonia. The thin dust is transported by

a) Settled volcanic ashes ‫رماد بركاني مستقر‬ b) Alluvial flooded plains ‫سهول الغرين المغمورة‬

c) Glacial dust ‫الغبار الجليدي‬ d) Coastal plain dunes ‫كثبان السهل الساحلي‬ 11. The present concentration ‫ التركيز الحالي‬of a hypothetic radioactive isotope ‫( النظائر المشعة‬xxGx) related to original concentration has been measured in geological units 2, 8 and 9. The half-life (t½) of xxGx is 50 million years. The geological unit 8 was formed… ago (1 Ma = 1 million years). a) 10 Ma b) 30 Ma c) 50 Ma

d) 70 Ma e) 90 Ma f) 110 Ma

12. The origin of geological unit 8 is necessarily related to… a) A sedimentary process dm‫العمليات الترسيب‬ b) An intrusive process ‫العمليات التداخلية‬ c) A faulting process ‫العمليات الصدعية‬ d) A volcanic process ‫العمليات البركانية‬

e) f) g) h)

An edaphic process ‫عمليات التربة‬ A glacial process ‫العمليات الجليدية‬ An orthomagmatic dike ‫القاطع المجماتي‬ A plutonic process ‫العمليات الباطنية‬

13. Which of the three disconformities ‫ عدم توافق‬shown in Figure 4 could be an angular discordance ‫?توافق زاوي‬ a) A c) C b) B d) None IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 5

14. Which of the following pairs of units in Figure 4 show evidence of a marine regression (‫?(األدلة على إنحسار البحر‬ (Mark all the right answers) a) 9>8 d) 6>5 g) 3>2 b) 8>7 e) 5>4 h) 2>1 c) 7>6 f) 4>3 i) None 15. Referring to Figure 4, which of the following is closest to the age of the folding ) ‫ (طي أو انثناء‬of unit 7? (You will need to plot the graph) a) 125-150 Ma d) 200-225 Ma b) 150-175 Ma e) 225-250 Ma c) 175-200 Ma After exploring the Atlantic coast of South-America, the Beagle paid a second visit to Tierra del Fuego and sailed toward the Pacific Ocean, across the Beagle Channel. 16. In this area, Darwin could have experienced) )‫ (شواهد‬the Antarctic Circumpolar Current )‫(تيارات القطب الجنوبي‬ (ACC) but could not suspect the existence) )‫ (ال يشك في وجود‬of the Antarctic Bottom Waters) ‫( مياه قاع القطب‬ )‫( الجنوبي‬AABW). Which of the following is most correct? a. ACC is a valuable wind for sailing )‫) رياح مفيدة لإلبحار‬and AABW is dangerous due to the presence of icebergs )‫(الجبال الجليدية‬ b. ACC was active in the times of Darwin and AABW is a recent current due to climate warming and Antarctic ice melting. c. ACC is very saline )‫ (مالح جدا‬and AABW has a very low salinity )‫(منخفض الملوحة‬ d. ACC is a wind driven current )‫ (تيارات ناتجة عن الرياح‬and AABW is a density driven current) ‫تيارات ناتجة عن‬ )‫اختالف الكثافة‬ 17. The Beagle channel is a valley excavated by Pleistocene glaciers )‫(وادي حفر بواسطة الجليديات‬and consequently it can be described as(‫… (بالتالي يمكن وصفه بأنه‬ a. A glacial eroded horn ‫(قرن محفور بواسطة‬ )‫الجليديات‬ b. A fjord inundated )‫(مضيق غمر‬by sea level rise c. A periglacial environment )‫(بيئة شبه جليدية‬

d. A fluvial invasion of glacial crevasses e. An isostatic subsidence valley ‫وادي ناتج عن‬ ‫هبوط بسبب قوى متماثلة‬

On 20th February 1835 the Beagle was in Valdivia when an earthquake hit the region. Darwin wrote in his journal: “This day has been remarkable in the annals of Valdivia for the most severe earthquake which the oldest inhabitants remember”. By 5th March, he landed in Concepcion (Chile) 36º52' S 73º01' W and found "That not a house in Concepcion or Talcuhano (the port )‫ )الميناء‬was standing, that seventy villages)‫ (سبعون قرية‬were destroyed )‫(دمرت‬, and that a great wave )‫ (الموجة الكبيرة‬had almost washed)‫ (غسل‬away the ruins)‫ (أطالل أو آثار‬of Talcuhano". 18. Given the three seismograms )‫ (السجالت الزلزالية‬and the provided map) ‫(الخريطة المعطاة‬, choose the location of the epicentre )‫(مركز الزلزال‬. [Choose a, b, c ,d or e in your answer sheet]

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 6

Station 1

S2 S waves

P waves P



Station 2

c d


Station 3

S1 e




Figure5.A. Map of a region of Chile, with the Pacific Ocean to the West and the Andes to the East. S1, S2 and S3 are three seismic stations. The points a-e show possible epicenters of an earthquake. B. Seismograms registered in stations S1-S3, with indication of the arrival times of P and S waves (in seconds).

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 7





Aprox. 6000 m

Along the journey )‫(رحلة‬, the Beagle visited many kilometres of coast. Look at figure 6 to answer questions 19 and 20:

Figure 6. Four simplified hypothetic types of coast profiles. 19. Which drawing is the best representation)‫ )توضيح‬of the Atlantic coast of Santa Fe (Argentina)? [Choose a, b, c or d in your answer sheet] 20. Which drawing is the best representation of the Pacific coast )‫ (شاطيء المحيط الهادئ‬of Concepción (Chile)? [Choose a, b, c or d in your answer sheet] Galapagos Islands are a milestone )‫ (معلم أو بصمة‬for Darwin and any later biologist. From an Earth Science point of view, they also represent a rather special setting )‫(حالة خاصة‬. The geological setting in Galápagos is similar to Hawaii

Figure 7. Simplified tectonic setting of Galapagos Islands. Arrows show plate movement.

21. Which of the following statements best describe the Galápagos Geological setting? a) They are on a Benioff plane ‫(عندما تنزلق صفحة تحت‬ ‫أخرى‬ b) They are on a mantle plume c) They are on a lithosphere isostasy rift d) They are on one transform fault ‫(صدوع تحويلية أو‬ )‫مماسية‬

22. The volcanism of Galapagos Islands is… a) Of the same age in all the islands b) Of random agein the archipelago ‫(عمر عشوائي‬ )‫في األرخبيل‬ c) Older in the west

d) Younger in the west e) Older in the east f) Younger in the east

By the time the Beagle arrived in the Cocos-Keeling Islands, Darwin had observed a lot of evidence of uplifting processes (seashells in mountains, volcanic islands, etc.) and he felt there must be evidence of subsidence somewhere to guarantee some Earth equilibrium. In fact, The Structure and Distribution of Coral Reefs was published in 1842 as the first part of the geology of the voyage of the Beagle. In his map of coral reefs he identified two main types of reefs: “Red for active volcanoes and blue for fringing reefs”. In the Cocos-Keeling Islands, Fitzroy probed the reef and produced a precise chart that remained the standard until World War II. IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 8

This precise survey and his observations allowed Darwin to develop an explanation of reef and atoll formation that is still accepted.

Cocos – Keeling Islands

Figure 8. Darwin's map of coral reefs. Some of his "red" reefs, associated to active volcanoes, are enclosed with doted lines. Some of his "blue" reefs, or fringe reefs, are enclosed with solid lines. Cocos-Keeling Islands are also marked. 23. The red reefs )‫( (الشعاب المرجانية الحمراء‬enclosed with dotted lines) of Darwin’s map are essentially related to a) Subduction zones)‫(المناطق اإلندساسية‬ d) Transforming faults )‫(االصدوع التحويلية‬ b) Dorsal zones e) Continental lithosphere ‫الغالف الصخري‬ c) Hot spots)‫(النقاط الساخنة‬ ‫تحت القارات‬ 24. The atolls )‫ ( الجزر البركانية‬are formed in… a) Extinct volcanoes )‫ (البراكين القديمة‬uplifted due to mantle plumes push b) The crater of active volcanoes, producing atoll ring of corals c) The slopes of extinct, subsiding volcanoes, with the corals growing to reach sun light d) Active volcanoes )‫(البراكين النشطة‬of low temperature e) Active explosive volcanoes )‫(البراكين المتفجرة النشطة‬ Along the trip)‫(الرحلة‬, Darwin didn’t pay much attention to stars, but it’s sure that Fitzroy did. On Sunday, 81 Aug 1236, the Beagle crossed the Equator )‫ (خط االستواء‬in his return trip )‫ (رحلة العودة‬to England. Along the trip, they could very often observe the constellations of the celestial equator)‫)اإلبراج النجمية‬, such as Orion. Among the stars of Orion, some are rather prominent stars ‫(نجوم‬ )‫بارزة‬, as Betelgeuse and Rigel. 25. Identify Betelgeuse in the map. [Choose a letter from A to H in your answer sheet] 26. Identify Rigel in the map. [Choose a letter from A to H in your answer sheet]

Figure 9. Simplified stellar map of constellation Orion

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 9

IESO 2014 – Study Case A. The Geological Journey of Charles Darwin – pg. 10