1. The Formation of the Solar System
2. The Age of the Earth
4. The Changing Earth
5. The Earth’s history
6. Life of Earth
3. The Sun and the planets were formed at the same time. There are some evidences:
All the planets move around the Sun on the same ecliptic plane
The planets move around the Sun in the same direction (counter-clockwise) and
the Sun revolves in the same direction, too.
4. Materials have been
distributed by the gravity
depending on their
The ones that have a high
melting point (refractory)
are close to the Sun
Mercury Venus Earth Mars
The ones that have a low
melting point (volatile)
are further away
Jupiter Saturn Uranus Neptune
5. After the Big Bang matter was concentrated in
different points, forming stars and nebulas (dust +
1. A star exploded becoming
2. A nebula appeared
3. The nebula rotated aund
flattened into a disc shape
4. The temperature rose due
to particles colliding. Nuclear
fusion began in the centre
The Sun appeared
6. The temperature
the most refractory
near the Sun
The most volatile far
away from the Sun
These materials (PLANETESIMALS) were joining together until the planets formed. This
process is called PLANETESIMAL ACCRETION
7. The heat generated melted much of
Activities 1, 2, 3, 4 page 51
8. Previous hypothesis
age of the Earth
James Ussher (17th
Lord Kelvin (19th
40 million years
John Joly (19th
100 million years
9. CURRENT ESTIMATION 4550 million years
DATING = It consists of estimating the age of an event or object or placing it in a
specific time or period.
10. Dating methods in
They determine the age
of the events or
They put materials or
events in chronological
order without specifying
Example 1 : Put the next events in chronological order:
Solution: A, B, C, D, E, erosion
11. Example 2 : Put the next events in chronological order:
Solution: 1, 2, 3, normal fault, erosion, 4
Solution: pink, red, erosion, orange, yellow, blue
12. Absolute dating methods: RADIOMETRIC DATING
Method used to date an object by comparing the number of
specific radiactive isotopes it contains
Some atoms lose particles from their nucleus in a process of disintegration.
This process happens at fixed speeds.
13. (período de semidesintegración)
The speed of disintegration is expressed as the HALF LIFE (T) of a substance. It is
the time required for half of a mass of radiactive isotopes to disintegrate.
15. Relative dating methods
The deposit of layers (or sedimentation) happens periodically.
The layers are deposited horizontally and have the same age in the whole layer.
Principle of superposition
Each layer is younger than the one below it and older
than the one above it
Principle of cross-cutting relationships
An event (fault, fold…) is younger than the rocks it
affected and older than the rocks it did not affect
Principle of faunal succession
The fossils contained in one layer are the same age as
the layer. So, each period in the history of the Earth
can be classified by a type of fossil Activities 5 and 6 page 51
16. PALEONTOLOGY = It is the part of geology that studies fossils.
FOSSILS = They are the remains of living beings or their activity
preserved in rocks.
Fossilization (it is a rare ocurrence)
An organism dies and its body lays on the ground
The soft parts are decomposed
Sediments cover the remains
Diagenesis takes place and the minerals of the sediments substitute
the atoms of the bones, shell…
The sedimentary rock is eroded and the fossil appears uncovered
17. Importance of
They provide temporal
A fossil species will only
appear in rocks for a
specific period of time
(when it lived)
Learn about the
conditions of a
(fósiles-guía): fossils of
species that existed for
short periods of time
over large areas
19. Theories in the
Isostatic movements, erosion….
There have been sudden
catastrophes that, in a
short space of time, have
changed the Earth
Slow and imperceptible
changes over millions of
years produce enormous
“The same geological
processes that are
observable today were
also responsible for the
changes on Earth in the
20. Theories accepted today:
• The changes on the Earth’s surface are mostly
• There are rare violent events which can also
affect the planet
Types of changes
Climate changes Warm periods/glacial
Sea level changes More or less land
Changes in the
distribution of the
continents due to
25. Based on the great changes that took place in the past, geologists have divided the
geological time (more than 4500 million years) into units:
EONS ERAS PERIODS
27. First rocks, first atmosphere and oceans were formed
Many meteorites bombarded the Earth
Lots of volcanic activity
First life forms probably existed at the end of the Eon
28. Most of the Earth was an ocean. Microcontinents.
First prokaryote cells.
29. Meteorite bombardment stopped.
Tectonic plate movement began.
1000 Ma ago one supercontinent (Rodinia) was formed.
Cryogenian period coldest period of the planet’s history (tillites have been found
in almost all continents).
30. Cyanobacteria appeared (autotrophic cells which formed rocks called stromatolites).
They did photosynthesis oxygen is accumulated in the atmosphere
Aerobians appeared first eukaryotic cells first multicellular organisms
Ediacaran fauna soft bodied organisms found in Australia
32. At the beginning (Cambrian) continents were separated.
They reunited in the Permian forming Pangaea.
First plants appeared on the land, followed by arthropods, amphibians and reptiles.
Many new species and extinctions.
Carboniferous: forest of giant ferns coal.
INDEX FOSSIL: TRILOBITES
34. Continents separated to reach their current location.
Rise in the global sea level half of the continents were submerged they were
covered by limestone and plankton PETROLEUM
250 Ma ago: trilobites extinction
656 Ma ago: dinosaurs + ammonites extinction, probably caused by a meteorite.
Reptiles were the dominant animals “Age of Reptiles”.
First mammals and first birds, first plants with flowers.
INDEX FOSSIL: AMMONITE AND BELEMNITES
37. Alpine Orogeny
Glacial + short interglacial periods many changes in the sea level
Dominant living beings: mammals and flowering plants
INDEX FOSSIL: NUMMULITES
Smilodon (sabre-toothed) in America
39. EON ERA PERIOD AGE LIFE FORMS AND FOSSILS GEOLOGY CLIMATE AND
PHANEROZOIC CENOZOIC QUATERNARY
“Age of Mammals and Birds”
“Age of Reptiles”
Current location of
Rise in the sea level
Forest of giant ferns (coal)
First eukaryotic cells
ARCHAEAN First prokaryotic cells Microcontinents
First biomolecules First rocks