GEOLOGIC TIME Earths History Compressed GEOLOGIC TIME Question

GEOLOGIC TIME Earth’s History Compressed:

GEOLOGIC TIME Question: Where did our modern ‘scientific method’ originate?

St. Thomas Aquinas (13 th century): “Faith and Reason”

GEOLOGIC TIME I. Early Efforts of Dating the Age of the Earth

GEOLOGIC TIME I. Early Efforts of Dating the Age of the Earth A. James Ussher (mid 1600's) 4004 B. C.

I. Early Efforts of Dating the Age of the Earth B. Georges Buffon (mid 1700's) 75, 000 yr C. Lord Kelvin (late 1800's) 20 -40 m. y.

I. Early Efforts of Dating the Age of the Earth D. Charles Walcott (1893) 75 m. y.

I. Early Efforts of Dating the Age of the Earth E. John Joly (1899) 90 m. y.

I. Early Efforts of Dating the Age of the Earth E. Henri Becquerel (1896) ‘Discovered Radioactivity of certain elements’

II. Constancy of Natural Laws

II. Constancy of Natural Laws A. Catastrophism • Georges Cuvier (late 1700's)

A. Catastrophism • Georges Cuvier (late 1700's) B. Uniformitarianism • James Hutton (late 1700's)

III. Types of Geologic Dating A. Relative Dating B. Radiometric Dating

III. Types of Geologic Dating A. Relative Dating 1. Law of Superposition

III. Types of Geologic Dating A. Relative Dating 1. Law of Superposition 2. Law of Original Horizontality

III. Types of Geologic Dating A. Relative Dating 1. Law of Superposition 2. Law of Original Horizontality 3. Law of Cross Cutting Relationships

III. Types of Geologic Dating A. Relative Dating 1. Law of Superposition 2. Law of Original Horizontality 3. Law of Cross Cutting Relationships 4. Law of Faunal Succession

III. Types of Geologic Dating A. Relative Dating 1. Law of Superposition 2. Law of Original Horizontality 3. Law of Cross Cutting Relationships 4. Law of Faunal Succession 5. Unconformities

III. Types of Geologic Dating 5. Unconformities – Disconformity – Angular Unconformity – Non Conformity

An Example……

III. Types of Geologic Dating B. Radiometric Dating 1. Types of decay

III. Types of Geologic Dating • alpha decay

III. Types of Geologic Dating • alpha decay

III. Types of Geologic Dating • beta decay

III. Types of Geologic Dating • beta decay

III. Types of Geologic Dating electron capture

III. Types of Geologic Dating electron capture

III. Types of Geologic Dating neutron capture N P

III. Types of Geologic Dating B. Radiometric Dating 1. Types of decay • alpha decay • beta decay • electron capture • neutron capture

An Example…. Parent U 238

An Example…. Parent U 238 92 protons 146 neutrons

An Example…. Parent U 238 → 8 alpha + 6 beta = ? 92 protons 146 neutrons

An Example…. Parent U 238 → 8 alpha 92 protons + 8 {lose 2 protons} + 8{lose 2 neutrons} 6 beta

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + 8 {lose 2 neutrons} - 16 protons - 16 neutrons + 6 beta

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + 8 {lose 2 neutrons} - 16 protons - 16 neutrons + 6 beta

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + 8 {lose 2 neutrons} - 16 protons - 16 neutrons + 6 beta 6 (add 1 proton)

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + + 6 beta 6 (add 1 proton) {lose 2 neutrons} - 16 protons - 16 neutrons + 6 protons

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + {lose 2 neutrons} - 16 protons - 16 neutrons + 6 beta 6 (add 1 proton) + 6 protons = - 10 protons - 10 atomic number

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + {lose 2 neutrons} - 16 protons - 16 neutrons - 32 atomic mass + 6 beta 6 (add 1 proton) + 6 protons = - 10 protons - 10 atomic number

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + {lose 2 neutrons} - 16 protons - 16 neutrons - 32 atomic mass U 238 – 32 = “X” 206 + 6 beta 6 (add 1 proton) + 6 protons = - 10 protons - 10 atomic number

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + {lose 2 neutrons} + 6 beta 6 (add 1 proton) - 16 protons - 16 neutrons - 32 atomic mass U 238 – 32 = “X” 206 92 protons – 10 protons = 82 protons + 6 protons = - 10 protons - 10 atomic number

An Example…. Parent U 238 → 8 alpha 8 {lose 2 protons} + {lose 2 neutrons} + 6 (add 1 proton) - 16 protons - 16 neutrons - 32 atomic mass U 238 – 32 = “X” 206 92 protons – 10 protons = 82 protons “X” 206 with 82 protons 6 beta + 6 protons = - 10 protons - 10 atomic number

U 238 – 32 = “X” 206 92 protons – 10 protons = 82 protons

An Example…. Parent U 238 → 8 alpha 206 Pb Atomic # = 82 + 6 beta = ?

III. Types of Geologic Dating B. Radiometric Dating 2. Half lifes, Parents, and Daughters

III. Types of Geologic Dating B. Radiometric Dating 2. Half lifes, Parents, and Daughters half life (def) n : the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)

C 14 → N 14 5730 years organic carbon

III. Types of Geologic Dating B. Radiometric Dating 3. An example

B. Carbon Dating

IV. Geologic Time