The document discusses the theory of planetesimals to explain the formation of the solar system and Earth. It describes how a gas and dust nebula collapsed into a disk, with matter accumulating in the center to form the sun. Remaining matter separated into rocky planets like Earth and gas giants due to temperature differences. Over time, planetesimals collided to form the planets. It then summarizes Earth's history, describing its formation and cooling, the development of its atmosphere and life, and the four eons that have passed since - Hadean, Archean, Proterozoic, and Phanerozoic.

1. THE HISTORY
OF THE EARTH
4º
SERGIO SALOBREÑA
LUCENA
MIJAS

2. ORIGIN OF THE SOLAR SYSTEM
THE CURRENTLY ACCEPTED THEORY TO EXPLAIN THE FORMATION OF THE
SOLAR SYSTEM, AND THE OWN EARTH IS THE THEORY OF THE
PLANETESIMALS:
1. A GAS AND DUST NEBULA, FLOATING IN SPACE WITH VERY SLOW
MOVEMENTS BETWEEN ITS PARTICLES TILL IT RECEIVED THE EXPANSIVE
WAVE OF THE EXPLOSION OF A NEARBY SUPERNOVA.
2. THE NEBULA BEGAN TO ROTATE MUCH FASTER, AND TO COLLAPSE IN A
SINGLE PLANE.
3. IN THE CENTER OF THE NEBULA, THE ACCUMULATION OF MATTER AND
THE CONTINUOUS SHOOTS INCREASED THE PRESSURE AND THE
TEMPERATURE, ALLOWING THAT THEY WILL BEGIN TO NUCLEAR
REACTIONS. THAT WAS BORN OUR SUN FROM A PROTOSOL.

3. ORIGIN OF THE SOLAR SYSTEM
4. OUR CENTRAL STAR ATTRACTED 99.85% OF THE MATTER AND GAS OF
THE SYSTEM, BUT THE REST WAS ABLE TO SEPARATE AND THROUGH
THE ROCK LINE, WHERE THERE WAS PIECE OF MATTER AND EVEN
FURTHER, AFTER THE FREEZING LINE GASES WERE SOLIDIFIED AS
WATER VAPOR, METHANE, ETC.
5. SMALL BITS OF MATTER, THEY WOULD BEGIN TO COLLIDE WITH LITTLE
VIOLENCE AND JOIN IN AGGREGATES OF GREATER SIZE CALLS
PLANETESIMALS, WHICH WOULD IMPACT THEMSELVES, INCREASING
SIZE UNTIL FORMING THE PLANETS.
6. THIS PROCESS WAS FASTER IN THE FORMATION OF THE EXTERNAL
PLANETS BECAUSE THERE WERE MUCH MORE GREAT AMOUNT OF
FLOATING PARTICLES. ONCE THESE PLANETS REACH A DETERMINED
SIZE, THEY BEGIN TO ATTRACT THE GAS AND MATTER THAT SURROUND
THEMSELVES WITH GRAVITATORY FORCES, BECOMING GASEOUS
GIANTS (EXTERNAL PLANETS).

4. ORIGIN OF THE SOLAR SYSTEM
7. IN THE AREA LOCATED BETWEEN THE ROCK LINE AND THE FREEZING
LINE, WHEN THE TEMPERATURE IS GREATER, GAS IS SCARCE AND THE
ROCK PARTICLES IN SUSPENSION ARE LESS ABUNDANT, SO THAT IT
TAKES MUCH MORE TIME TO FORM THE PLANETS FROM
PLANETESIMALS. IN ADDITION TO THE NO GAS, THERE CAN ONLY
ATTRACT ROCK FRAGMENTS, SO THE INTERIOR PLANETS WILL BE LESS
SIZE THAN THE EXTERNAL PLANETS.
8. THE EARTH IN ITS FIRST STAGES WAS ACCOMPANIED BY ANOTHER
PROTOPLANET CALLED CEIA, FINALLY COLLISED, WINNING THE EARTH
MASS AND A MOON. FINALLY 4500 M.A. AGO, THE EARTH IS STABILIZED
AND BECOMES ONE OF THE INTERNAL PLANETS.

5. ORIGIN OF THE SOLAR SYSTEM
7. IN THE AREA LOCATED BETWEEN THE ROCK LINE AND THE FREEZING
LINE, WHEN THE TEMPERATURE IS GREATER, GAS IS SCARCE AND THE
ROCK PARTICLES IN SUSPENSION ARE LESS ABUNDANT, SO THAT IT
TAKES MUCH MORE TIME TO FORM THE PLANETS FROM
PLANETESIMALS. IN ADDITION TO THE NO GAS, THERE CAN ONLY
ATTRACT ROCK FRAGMENTS, SO THE INTERIOR PLANETS WILL BE LESS
SIZE THAN THE EXTERNAL PLANETS.
8. THE EARTH IN ITS FIRST STAGES WAS ACCOMPANIED BY ANOTHER
PROTOPLANET CALLED CEIA, FINALLY COLLISED, WINNING THE EARTH
MASS AND A MOON. FINALLY 4500 M.A. AGO, THE EARTH IS STABILIZED
AND BECOMES ONE OF THE INTERNAL PLANETS.

6. THE HISTORY OF THE EARTH
• SINCE ITS FORMATION 4600 M.A. AGO MULTITUDE OF EVENTS ON THE
EARTH
HAS HAPPENED, WHICH HAS ALLOWED TO FRACTION TIME IN EONS, ERAS
AND
PERIODS FOR ITS BEST STUDY. CURRENTLY 4 EONS ARE RECOGNIZED:
1. HADIC EON (4500-3600 M.a.)
2. ARCHAIC EON (3600-2500 M.a.)
3. PROTEROZOIC EON (2500-540 M.a.)
4. FANEROZOIC EON (540-NOW)

7. HADIC EON
CALLED IN HONOR TO HADES, HELL IN GREEK MYTHOLOGY, DUE TO THE
CONDITIONS OF THE EARTH DURING THIS TIME. THE EARTH IS IN ITS
FORMATION PHASE, METEORITES FALL CONTINUOUSLY INCREASING ITS
TEMPERATURE, BEING INITIALLY AN AUTHENTIC SEA OF LAVA TO MORE THAN
1000º C.
THE EARTH BEGINS TO COOL AND A VERY UNSTABLE SOLID BARK IS
FORMED, BECAUSE IT IS ON A FUNDED LAYER AND THE IMPACT OF
METEORITES. GASES RELEASED FROM THE LAVA WILL GENERATE THE
ATMOSPHERE (RICH IN CO2 AND WATER VAPOR) AND THE HYDROSPHERE.
THE OLDEST ROCKS FORMED AT THE END OF THIS STAGE, 3600 M.a. AGO.

8. HADIC EON

9. HADIC EON
THE APPEARANCE OF WATER ON THE EARTH IS A MYSTERY
STILL, IT IS CURRENTLY BELIEVED THAT MOST OF THE WATER
ARRIVED IN ASTEROIDS AND COMETS WITH HIGH CONTENT IN
WATER THAT COLLIDED WITH THE EARTH IN FORMATION. THIS
WATER WAS EVAPORATED ON THE SURFACE, AND THE
WATER VAPOR ASCENDED IN IMMENSE AMOUNTS FORMING
THICK CLOUDS, TRIGGING A HUGE DILUVIUM THAT LAST
MILLION YEARS.

10. ARCHAIC EON
GEOLOGY: THE FIRST ROCKS ARE METAMORFICAL OR
VOLCANIC, WHILE THE ATMOSPHERE IS FORMED BY
METHANE (CH4) CARBON DIOXIDE (CO2) AND AMMONIA (NH3).
WEATHER: THE SUN IRRADIAED LESS ENERGY THAN NOW,
HOWEVER, THE TEMPERATURE WAS ABOUT 30 ° C ON THE
SURFACE AND BETWEEN 30-40 ° C IN THE OCEAN DUE TO THE
GREAT GREENHOUSE EFFECT OF THE CO2 RICH
ATMOSPHERE.
LIFE: THE FIRST LIVING BEINGS CAME UP 3500 M.a. AGO. THEY
WERE PROCARIOTS CELLS, FILAMENT BACTERIA LIVING IN
THE ARCHAIC OCEANS. THE PHOTOSYNTHESIS PROCESS
COMES UP AND THE ATMOSPHERE ENRICHES IN O2.

11. ARCHAIC EON

12. ARCHAIC EON

13. PROTEROZOIC EON
GEOLOGY: EMERGED LANDS JOIN FORMING THE SUPERCONTINENT PANGEA
I, WHICH BEGINS TO FRAGMENT WHEN THIS EON IS ENDED.
CLIMATE: THERE WERE BIG CLIMATE SWINGS, WITH TWO BIG GLACIATIONS,
AT THE BEGINNING AND AT THE END OF EON.
LIFE: CYANOBACTERIES IN LITTLE DEEP WATERS FORM A VERY
CHARACTERISTIC ROCKY STRUCTURES CALLED STROMATOLITES. THE
ATMOSPHERE BY ACTION OF THE PHOTOSYNTHETIC BACTERIA GOES FROM
BEING REDUCING TO OXIDIZING.
1400 M.a. AGO THE EUCHARIOT CELLS BEINGS APPEAR AND SHORTLY AFTER
THE PLURICELLULAR ORGANISM BEINGS. AT THE END OF THE EON THE
GREAT VARIETY OF INVERTEBRATES PROLIFING IN THE OCEANS THAT
CONSTITUTE THE FAUNA OF EDIACARA, DISAPPEARED AFTER A GREAT
EXTINCTION.

14. PROTEROZOIC EON

15. PROTEROZOIC EON

16. FANEROZOIC EON
THE FANEROZOIC EON COVERS THE LAST 540 M.a. AND IS DIVIDED IN 3 ERAS:
•PALEOZOIC: INCLUDES 6 PERIODS: CAMBRIAN, ORDOVICIAN, SILURIAN,
DEVONIAN, CARBONIFEROUS AND PERMIAN.
•MESOZOIC: INCLUDES 3 PERIODS: TRIASSIC, JURASSIC AND CRETACEOUS.
• CENOZOIC: INCLUDES 2 PERIODS: TERTIARY AND QUATERNARY.

17. PALEOZOIC
• GEOLOGY: IN THE CAMBRIAN, PANGEA I IS FRAGMENTED IN VARIOUS CONTINENTS (GONDWANA,
LAURENTIA, BALTIC AND HARMORIC). IN THE CARBONIFEROUS, THEY MEET AGAIN, FORMING PANGEA
II, SURROUNDED BY AN ONLY OCEAN: PANTHALASA. IN THIS COLLISION BETWEEN CONTINENTS GIVES
PLACE TO TWO OROGENIES: CALEDONIAN AND HERCINIAN.
• CLIMATE: THERE WERE TWO BIG GLACIATIONS, IN THE ORDOVICIAN AND IN THE PERMIAN. BETWEEN
BOTH GLACIATIONS THE CLIMATE WAS WARM AND HUMID, DEVELOPING THE VEGETATION OVER THE
EARTH, UNTIL CREATING LARGE FORESTS IN THE CARBONIFEROUS, WHICH HAVE GIVEN PLACES TO
THE CURRENT COAL DEPOSITS.
•ANIMAL LIFE: THE PALEOZOIC BEGINS WITH THE "CAMBRIAN EXPLOSION", THE FEW LIFESTYLES THAT
SURVIVED THE LAST EXTINCTION ARE FOUND WITH A GREAT ABUNDANCE OF RESOURCES AND
MULTITUDE OF HABITATS WHICH UNDERTAKED THE RISE OF LIFE IN THE OCEANS. MANY EXISTING
ANIMAL GROUPS APPEAR TODAY: SPONJES, WORMS, MOLLUSCS, ECHINODERMS, ARTROPODS
(TRILOBITES, INSECTS, ARACHNIDS) AND VERTEBRATES. BETWEEN THE FIRST VERTEBRATES IN THE
SILURIAN AND DEVONIAN THE ARMOURED FISHES ARE CHARACTERISTIC.
SOME FISHES ADAPT TO THE EARTH AND MODIFY THEIR BODY, WHEN PLACING THE AMPHIBIANS,
WHICH THE REPTILES ARE DERIVED THEN (SECOND HALF OF THE CARBONIFEROUS).

18. PALEOZOIC
• VEGETABLE LIFE: THANKS THAT THE OZONE LAYER HAS ALREADY BEEN
FORMED, A FEW SEAWEEDS BEGIN TO CONQUER THE EARTH, THEN THE
MUSHROOMS APPEARED AND LATER THE FIRST VASCULAR PLANTS: THE
MUSGES. AFTER THE ARBORESCENT FERNS AND GYMNOSPERMS APPEAR
(PINES, GIANTS SEQUOIAS, FIR TREES ...) FIRST PLANTS WITH POLLEN AND
SEEDS, BUT WITHOUT FLOWERS.
IN THE PALEOZOIC, THERE WERE 3 GREAT EXTINCTIONS: END OF THE
ORDOVICIAN, DEVONIAN AND PERMIAN. THE EXTINCTION OF THE PERMIAN IS
THE GREATEST EXTINCTION THAT LIFE IN THE PLANET HAS SUFFERED,
BETWEEN OTHERS TOTALLY DISAPPEAR THE TRILOBITES AND OTHER
MARINE INVERTEBRATES, AND THE GREAT VARIETY OF FERNS IS REDUCED
TO A FEW GROUPS.

19. CAMBRIAN EXPLOSION

20. PALEOZOIC FAUNA
ANOMALOCARIS TRILOBITES
ARMOURED FISH
HEMICYCLASPIS

21. PALEOZOIC

22. PALEOZOICO

23. MESOZOIC
• GEOLOGY: PANGEA II FRACTURES IN THE TRIASSIC, ORIGINATING LAURASIA AND GONDWANA, WHICH
IN THE JURASSIC LAURASIA FRAGMENTS: EURASIA AND NORTH AMERICA AND GONDWANA: SOUTH
AMERICA, AFRICA, INDIA, AUSTRALIA AND ANTARTIC.
• CLIMATE: AT THE BEGINNING PREDOMINATED A DRY AND CONTINENTAL CLIMATE, BY FRAGMENTING
PANGEA II A GENERALIZED TROPICAL CLIMATE IS ORIGINATED.
• LIFE:. DUE TO THE INITIAL ARIDITY, ORGANISMS OF HUMID ENVIRONMENTS AS FERNS AND
AMPHIBIANS ARE BEING REPLACED BY OTHER LESS DEPENDENTS OF WATER AS ARE GYMNOSPERMS
(PINES, FIRS, SEQUOIAS ...) AND REPTILES. THE MESOZOIC IS KNOWN AS THE DINOSAURS ERA.
ALSO THE CHARACTERISTICS OF THIS AGE ARE THE AMMONITES, CEPHALOPOD MOLLUSCS PROVIDED
BY CALCAREOUS SHELL, THE FLYERS REPTILS OF WHICH EVOLVED THE FIRST BIRD ARCHAEOPTERYX
WITH FEATHERS, BUT WITH TEETH, CLAWS AND REPTIL TAIL.
THE DINOSAURS ERA CONCLUDES WITH AN EXTINCTION THAT AFFECTS DINOSAURS AND AMMONITES.
THE MOST ACCEPTED THEORY IS THE FALL OF A METEORITE THAT PRODUCED AN ENVIRONMENTAL
CATASTROPH AT THE PLANETARY LEVEL. THE ACCUMULATION OF PLANCTON IN THE MARINE FUNDS
ORIGINATES THE CURRENT PETROLEUM DEPOSITS.

24. MESOZOIC

25. MESOZOIC

26. MESOZOIC
PURGATORIUS

27. CENOZOIC
• GEOLOGY:THE SHAPE AND POSITION OF THE CONTINENTS AT THE BEGINNING OF THE CENOZOIC IS
VERY SIMILAR TO THE CURRENT. INDIA SHUTS WITH ASIA AND IS UNITED TO IT. THE ALPINE OROGENY
ORIGINS THE BETTIC CORDILLERA, ATLAS IN THE NORTH OF AFRICA, THE PYRENEES, THE ALPS, THE
URALS, HIMALAYA, THE ANDES, THE ROCKY MOUNTAINS ...
• CLIMATE: AT THE BEGINNING THE CLIMATE WAS WARM AND WET, AND THERE WAS NO ICE IN THE
POLAR CAPS. IN THE QUATERNARY GLACIATIONS OCCUR DUE TO VARIATIONS IN THE GROUND ORBIT.
IN THIS TIME THE MAJOR PART OF THE PETROL IS FORMED, BY PLANCTON WHEN DYING IT IS BURIED
IN MUD AND IS DECOMPOSED BY ACTION OF ANAEROBIAN BACTERIA.
• LIFE: IN THE TERTIARY THE ANGIOSPERMS APPEAR (PLANTS WITH FLOWERS) AND REACH A GREAT
DEVELOPMENT QUICKLY. IN THE ANIMALS THE NUMMULITES AND THE GIANT SHARK CARCHARODON
MEGALODON ARE CHARACTERISTIC. BUT THE ANIMALS WITH GREATER SUCCESS WERE BIRDS AND
MAMMALS, WHICH OCCUPIED THE PLACES THAT THE DINOSAURS LEFT FREE. SOME EVEN RETURN TO
THE SEA GIVING PLACES TO DOLPHINS, WHALES, SEALS ...
IN THE QUATERNARY THE HOMINIDS APPEAR IN AFRICA, LIVING WITH MAMUTS, SABER-TOOTHED
TYGER AND THE CAVERNARY BEAR.

28. CENOZOIC

29. THE EARTH A CHANGING PLANET
GEOSPHERE DISCLOSES CHANGES DUE TO THE ACTION OF DIFFERENT GEOLOGICAL
AGENTS (CHANGES IN THE RELIEF). THE BIOSPHERE HAS ALSO BEEN MODIFIED OVER
TIME, AS THE FOSSIL RECORD REVEALS. THE HYDROSPHERE AND THE ATMOSPHERE
HAVE ALSO CHANGED.
1. CHANGES IN THE ATMOSPHERE: THE ATMOSPHERE WAS CREATED IN THE ARCHAIC
AS A RESULT OF THE INTENSE VOLCANIC ACTIVITY. THEREFORE, THE PRIMITIVE
ATMOSPHERE WAS FORMED BY THE SAME GASES THAT TODAY COME OUT OF THE
VULCANS: WATER VAPOR, CO2, CH4, CO, NH3, SH2, SO2, HYDROGEN AND NITROGEN.
THERE WASN´T OZONE LAYER, LIFE ONLY DEVELOPED IN THE OCEANS, WHERE A
BACTERIA GROUP BEGAN TO PERFORM A NEW PROCESS THAT USED THE LIGHT AS A
SOURCE OF ENERGY AND GENERATED OXYGEN AS WASTE PRODUCT.
THE OXYGEN DIFFUSED FROM THE OCEANS TO THE ATMOSPHERE, WHERE IT WAS
COMBINED BY FORMING OZONE AND GENERATING A PROTECTIVE LAYER ON THE
ULTRAVIOLET RADIATION, WHICH ALLOWED THE EXIT OF WATER LIFE TO THE
CONTINENT.

30. THE EARTH A CHANGING PLANET
2. CLIMATE CHANGES: THE CLIMATE HAS EXPERIENCED NOTABLE CHANGES THROUGHOUT THE
HISTORY. DURING THE MOST PART OF TIME, THE EARTH HAS HAD A WARM CLIMATE, EVEN IF IT HAS
SUFFERED ALTERATIONS, TWO OF ITS MAIN CAUSES HAVE BEEN:
A) THE GLACIATIONS: ARE PERIODS OF COLD CLIMATE THAT APPEAR SPORTSLY THROUGHOUT THE
HISTORY. 7 GREAT GLACIATIONS HAVE HAPPENED FROM 2300 M.A. UP TO 10,000 YEARS. ITS ORIGIN
IS DUE TO A SET OF FACTORS SUCH AS: ALTERATIONS IN THE ISSUANCE OF HEAT OF THE SUN,
THE CHANGES IN THE INCLINATION OF THE AXIS OF THE PLANET AND THE CHANGE OF THE OCEAN
CURRENTS, DUE TO THE CONTINENTAL DERIVATIVE.
B) THE INCREASE IN THE GREENHOUSE EFFECT: THE AVERAGE TEMPERATURE OF THE EARTH IS
14ºC, IN PART THANKS TO THE GREENHOUSE EFFECT. GASES LIKE CO2, CH4 AND WATER VAPOR
(GREENHOUSE GASES - GHG) AVOID THE OUTPUT OF THE SOLAR RADIATION THAT IS RETURNED
TO THE GROUND SURFACE.
HUMAN SINCE THE INDUSTRIAL REVOLUTION HAS INCREASED THE CONCENTRATION OF GHG
IN THE ATMOSPHERE FOR THE MASS FOSSIL FUEL CONSUMPTION. THIS IS ORIGINATING IN
THE CURRENT RISE OF THE SEA LEVEL, CHANGES IN THE MIGRATORY ROUTES OF THE BIRDS,
AND IN THE DISTRIBUTION AND REPRODUCTIVE HABITS OF PLANTS AND ANIMALS.

31. EXERCISES
1. DO YOU THINK THAT THE AFFIRMATION THAT THE HUMAN IS PRODUCING
THE FIRST GREAT CLIMATE CHANGE IS CORRECT?
2. WHAT ARE THE CFCs? WHAT EFFECTS DO THEY OZONE LAYER?
3. WHAT ARE GLACIATIONS? WHAT CONSEQUENCES DID YOU HAVE IN THE
PAST?
4. WHAT IS THE GAIA THEORY? WHY DOES IT GENERATE SO MUCH DISPUTE?

32. FOSSILS
FOSSILS ARE REMAINS OF LIVING BEINGS OR OF THEIR ACTIVITY
(FOOTPRINTS = IGNITES OR EXCREMENTS = COPROLYTES), THAT AFTER A
SERIES OF CHEMICAL TRANSFORMATIONS HAVE BEEN PRESERVED INSIDE
SEDIMENTARY OR METAMORTIC ROCKS. PALEONTOLOGY IS THE SCIENCE
THAT IS STUDYING THEM.
THE GUIDE FOSSILS ARE USEFUL TO DETERMINE THE AGE OF THE ROCKS
WHERE THEY ARE FOUND, FOR THEY HAVE 3 CONDITIONS:
A) THEY LIVED FOR BRIEF PERIODS OF TIME, SO THEY APPEAR IN STRATES
OF CONCRETE AGES.
B) THEY ARE IN MANY PLACES OF THE PLANET, SO WHEN THEY LIVED THEY
HAD A GREAT GEOGRAPHICAL DISPERSION.
C) THEY WERE VERY ABUNDANT OR FOSSILIZED EASILY.

33. GUIDE FOSSILS
THE MOST FEATURE GUIDE FOSSILS ARE:
• TRILOBITES: MARINE ARTHROPODS OF PALEOZOIC PROVIDED WITH A SHELL DIVIDED
IN 3 LOBBIES. IN THE SIERRA OF CÓRDOBA, STRATES HAVE BEEN FOUND WITH THE
OLDEST TRILOBITES IN EUROPE.
• GRAPTOLITES: MICROSCOPIC MARINE ORGANISMS THAT FORMED COLONIES. THEY
ARE CHARACTERISTICS OF THE FIRST HALF OF THE PALEOZOIC. THEY APPEAR ON
BLACK BOARDS AND APPEAR WHITE DENTED TRACES. IN ANDALUSIA THERE ARE
DEPOSITS IN SIERRA MORENA.
• AMMONITES: THEY ARE GUIDE FOSSILS OF THE MESOZOIC. THEY ARE MARINE
CEPHALOPOD MOLLUSCS WITH A SHIELD SPLITED IN SPIRAL AND DIVIDED IN CAMERAS.
IN ANDALUSIA, THEY HAVE FOUND IN THE BETTIC EXTERNAL AREA.
• CALAMITES: THEY ARE GIANT FERNS THAT LIVE IN THE CARBONIFIER. REACHED UP TO
30 METERS.
• NUMMULITES: UNICELULAR PROTOZONS WITH SPRAYED AND SPRAY SHAPED SHELLS.
FOSSILS GUIDE TO THE TERTIARY MARINE FUNDS.

34. GUIDE FOSSILS
TRILOBITES GRAPTOLITES

35. GUIDE FOSSILS
CALAMITES NUMMULITES

36. TIME IN GEOLOGY
•ABSOLUTE DATING: CONSISTS OF FINDING THE SPECIFIC DATE IN WHICH A
GEOLOGICAL PHENOMEN HAPPENED OR A ROCK WAS FORMED. GENERAL
RADIOMETRIC METHODS ARE USED BY RADIOACTIVE ISOTOPES. THE MOST KNOWN ARE
THE CARBON 14 AND URANIUM 238 METHODS.
•RELATIVE DATING: ALLOWS TO ORDER IN TIME THE MATERIALS OR GEOLOGICAL
PHENOMENA, FROM THE OLDEST TO THE MOST MODERN, BUT WITHOUT PRECISING THE
EXACT AGE OF EACH ONE. IT IS BASED ON 3 PRINCIPLES:
A) SUPERPOSITION OF LAYERS PRINCIPLE: EACH STRATUM IS MORE MODERN THAN
THE ONE BELOW AND OLDER THAN THE ONE THAT IS FINDED ABOVE.
B) SUPERPOSITION OF GEOLOGYCAL EVENTS PRINCIPLE: EACH GEOLOGICAL
PHENOMENON IS MORE MODERN THAN THE MATERIALS THOSE IT AFFECTED, AND
OLDER THAN THOSE AFFECTING HIM.
C) CONTINUITY PRINCIPLE: A STRATA HAS THE SAME AGE IN ALL PLACES WHERE IT IS
FOUND.

37. INTERPRETATION OF GEOLOGYCAL CUTS
THE GEOLOGICAL HISTORY OF A REGION CAN BE INTERPRETED FROM GEOLOGICAL
CUTS THAT ARE SCHEMATIC DRAWINGS BASED ON THE PRINCIPLES OF RELATIVE
DATING, AND WHICH MAY ALSO COME IN ACCOMPANYING CHARACTERISTIC FOSSILS
THAT WILL ALLOW IDENTIFYING THE PERIOD IN WHICH EACH STRATUS WAS FORMED.
THE FOLLOWING STEPS ARE FOLLOWED FOR INTERPRETATION:
1. ORDER MATERIALS FROM OLDER TO MORE MODERN.
2. IDENTIFY THE DEFORMATION PHASES (FOLDS, GEOLOGYCAL FAULTS ...) THAT HAVE
BEEN ABLE TO FOLD AND FRACTURE THE STRATUMS.
3. DESCRIBE THE GEOLOGICAL HISTORY OF THE REGION.

38. GEOLOGICAL HISTORY 1

39. HISTORIA GEOLOGICA 1
1. ORDER MATERIALS FROM OLDER TO MORE MODERN: THE ORDER OF
DEPOSITION OF MATERIALS WOULD BE, ACCORDING TO THE
SUPERPOSITION LAYERS PRINCIPLE : 3-2-6-7-9-4-8-5-1.
2. IDENTIFY THE DEFORMATION PHASES: AFTER THE DEPOSITION OF 8, A
FOLDING IS PRODUCED THAT AFFECTS ALL THE FIRST SERIES OF
SEDIMENTATION, ACCORDING TO THE PRINCIPLE OF SUPERPOSITION OF
PHENOMENA.
3. DESCRIBE THE GEOLOGICAL HISTORY OF THE REGION :
A) THE MARINE SEDIMENTATION OF THE SERIES 3,2,6,7,9,4,8 IS PRODUCED IN
THE MESOZOIC ERA.
B) A FOLDING CAUSED THE INCLINATION OF THE WHOLE SERIES TO THE
NORTH, AND THE MATERIALS 2-6-7-9-4-8 EMERGED AND THEY SUFFERED
EROSION.
C) SINK OF THE BASIN, WHICH RETURNS THE MATERIALS UNDER WATER AND
SEDIMENTATION OF A 2nd SERIES COMPOSED BY 5-1.
D) MARINE REGRESSION AND EROSION OF 1 (ARRECIFAL LIMES).