created by Jackelyn Diaz from University of Southeastern Philippines taking Bachelor of Science in Secondary Education Major in Biological Science.

1. Tidal Theory
By: Jackelyn Diaz
BSEd-Bio. Sci.II

2. Tidal theory-- a theory of the evolution of a
celestial body that is based on the action of tidal
forces; specify
: such a theory explaining the moon's
evolution.
It is the application of continuum mechanics to
interpret and predict the tidal deformations of
planetary and satellite bodies and their atmospheres
and oceans, under the gravitational loading of another
astronomical body or bodies. It commonly refers to
the fluid dynamic motions for the Earth's oceans.

3. Tides—motion caused by the
gravitational attraction
between the earth, moon and
sun.
Newton (Theory of Gravity)—
tides are caused by a differential
gravitational pull.

4. Spring tides—sun, moon and earth
are all aligned. The tides are high. It
occurs twice a month during full
moon and new moon.
♥The gravitational pull of the moon
and sun are combined. At these
times, the high tides are very high
and the low tides are very low.

6. Neap tides—moon and sun
are at right angles to each
other. Tidal extremes are
reduced. It occurs during 1st
and 3rd quarter of the moon.

8. Absolute
and
Relative
Dating

9. Relative Dating—It is the science
determining the relative order of past
events, without necessarily
determining their absolute age.
♦It is when you know the age of a
certain rock layer is by comparing the
fossils.
♦It can only determine the sequential
order in which a series of events
occurred, not when they occur.

10. • Superposition: The most basic concept used in relative
dating is the law of superposition. Simply stated, each
bed in a sequence of sedimentary rocks (or layered
volcanic rocks) is younger than the bed below it and
older than the bed above it. This law follows two basic
assumptions: (1) the beds were originally deposited
near horizontal, and (2) the beds were not overturned
after their deposition.
• Faunal Succession: Similar to the law of superposition is
the law of faunal succession, which states that groups of
fossil animals and plants occur throughout the
geologic record in a distinct and identifiable order.
Following this law, sedimentary rocks can be "dated"
by their characteristic fossil content. Particularly useful
are index fossils, geographically widespread fossils that
evolved rapidly through time.

11. Crosscutting Relationships: Relative ages of rocks and
events may also be determined using the law of
crosscutting relationships, which states that geologic
features such as igneous intrusions or faults are
younger than the units they cut across.
Inclusions: Inclusions, which are fragments of older
rock within a younger igneous rock or coarse-grained
sedimentary rock, also facilitate relative dating.
Inclusions are useful at contacts with igneous rock
bodies where magma moving upward through the
crust has dislodged and engulfed pieces of the older
surrounding rock.

12. Determining Relative Age
• Extrusion—it’s a lava hardens on the
surface . It’s younger than the rocks
below it.
• Intrusion—magma cools and hardens
into a mass of igneous rock. It is always
younger than the rock layers around
and beneath or it can be determined
that the igneous intrusion is younger
than the sedimentary rock.

13. Absolute dating is the process of
determining a specific date for an
archaeological or paleontological
site or artifact or knowing exactly
how old a rock layer is.
♥Absolute dates do not necessarily
tell us when a particular cultural
event happened, but when taken as
part of the overall archaeological
record they are invaluable in
constructing a more specific
sequence of events.

14. Determine the Absolute Age
Potassium-Argon Dating-- Potassium is common
in rocks and minerals Potassium-40 is a
radioactive isotope of potassium that decays into
argon-40. The half-life of potassium-40 is 1.3
billion years, far longer than that of carbon-14,
allowing much older samples to be dated.
Carbon-14 Dating--Sediments less than about
50,000 years old that contain organic material can
be dated based on the radioactive decay of the
isotope Carbon 14.
For example, shells, wood, and other material
found in the shoreline deposits of Utah's
prehistoric Lake Bonneville have yielded absolute
dates using this method.

15. William Smith
• discovered regular order of occurrence of fossils in rock layers.
While digging the Somerset Coal Canal in southwest England, he
found that fossils were always in the same order in the rock layers.
• As he continued his job as a surveyor, he found the same patterns
across England.
• He also found that certain animals were in only certain layers and
that they were in the same layers all across England.
• Due to that discovery, Smith was able to recognize the order that
the rocks were formed.
• Sixteen years after his discovery, he published a geological map of
England showing the rocks of different geologic time eras.

16. Planetesimal Hypothesis
• Planetesimal—any of innumerable small bodies
of accreted gas and dust thought to have orbited
the Sun during the formation of the
planets. These are solid objects thought to exist
in protoplanetary disks and in debris disks.
• Planetesimal hypothesis—hypothesis that the
planets and satellites of the solar system were
formed by gravitational aggregation of
planetesimals.

17. Planetesimal hypothesis
• Geologist Chamberline and astronomer
Moulton in early 20th century at the
University of Chicago.
• There hypothesis called for close passage
of another star past our sun.
• The pull of the intruder’s gravity field
presumably extracted solar gaseous
materials, which 1st condensed in space to
form small bodies called planetesimals.

18. The countless numbers of these cold
asteroid like bodies tens to hundreds of
kilometer in diameter aggregated to
form planets. As the planets grew, their
strengthening gravity fields attracted
still more particles.
Tertiary planets—Mercury, Venus,
Earth and Mars.
Jovian Planets—Jupiter,Saturn,
Uranus and Neptune

19. •The planets evolved from a cloud of
planetesimals which revolved around the sun.
♥The planetesimals, the tiny cosmic
fragments collided with each other and
united together to form larger bodies which
became planets and satellites revolving
around the sun. This idea was that of a solid
origin of the earth and the other planet and
satellites to start with. During the near-
collision, hot gases were pulled out of both
stars and the gases then condensed.

20. ♦the planetesimals formed within a spiral disk
of dust and gas surrounding a central nucleus.
♦Their gravitational attraction eventually
caused the planetesimals to coalesce into
protoplanetary disks from which larger
objects such as planets, asteroids, and satellites
were formed, while the nucleus coalesced into
the Sun.

21. • Viktor Safronov
—his planetary hypothesis states that
planets form out of dust grains that
collide and stick to form larger and
larger bodies.
When the bodies reach sizes of
approximately one kilometer, then they
can attract each other directly through
their mutual gravity, aiding further
growth into moon-sized protoplanets
enormously.

22. End..