GEOL 1 LE 2 | Perspectives from Earth History

Man

A recent agent of changea recent agent of change

“death of planet Earth”

Loss of internal heat and its consequence called _____________ form part of the destiny of this planet.

10000 Years

Amount of time before a fault or volcano is considered inactive after showing no activity. Similarly, age of remains before being considered a “fossil”

Anthropocene

Proposed (accepted) addition to the Geologic Timescale, splitting the Holocene Epoch into two by the major impact of man on the planet.

4.56 Billion Years Old

Age of Earth

Slow to Fast

Rates of Change of Earth

2-2.5 Mya (0.04% of Geologic Time)

The duration that Man has been on the Planet.

• Fossils

• Earth materials

Evidences used to record Earth History

Fossils

Actual remains, imprints, and traces of formerly living organisms older than 10K years

• Actual remains (e.g., from Amber, Tar pits, Ice)

• Body fossils: casts, molds

• Trace (Ichnofossils): manifestation of activity--- burrows, coprolites, tracks

• Chemical: molecules

Types of Fossils

Living Fossils

An organism that has remained essentially unchanged from earlier geologic times and whose close relatives are usually extinct

• Eubacteria

• Archaea

• Eucarya

3 Major Domains of Life

Eucarya

Life with Eukaryotic Cells: with nuclear membrane

Many kinds of membranous organelles in cell

Eubacteria and Archaea

Life with Prokaryotic Cells: no nuclear membrane

Kerogen

Photosynthetic byproduct indicating possible photosynthetic life over 3.5Bya

Banded Iron Formations (BIF)

Ferric Iron-rich sediments in the ocean noting reaction of iron with oxygen-rich water. This suggests a significant amount of oxygen in the atmosphere at least 2.6 Bya

Phanerozoic

The Age of Visible/Evident Life (First Abundant Skeletons)

Organisms have developed preservable hard parts.

Vendian Revolution

End of the Proterozoic; Ocean iron now depleted, free O2 build up in the ocean and atmosphere forming the ozone.

Photosynthesizers, Eukaryotes, appear and tolerate/use O2. Prokaryotes dwindle.

Vendian/Ediacara Fauna

These were confirmed to be multicellular organisms

A set of remarkable animal (fauna) fossils first discovered in the Ediacara Hills of Southern Australia

Fossilized imprints of what were apparently soft-bodied organisms, preserved mostly on the undersides of slabs of quartzite and sandstone.

Most were round, disc-shaped forms that Sprigg dubbed "medusoids" from their seeming similarity to jellyfish. Others, however, resembled worms, arthropods, or even stranger things.

Vendian biota

(recently confirmed to be multicellular)

These soft-bodied fossils of the first animals from the Vendian are also known as the __________.

• It is the first appearance of a group of large fossils in the rock record.

• It gives us a good look at the first animals to live on Earth.

Phanerozoic Eon

540Mya - Present

Consisting of

• Paleozoic

• Mesozoic

• Cenozoic

Precambrian Eon

Eon subdivided into Hadean, Archean, and Proterozoic eons dominated by single-celled organisms

Cambrian

Start of the Phanerozoic Eon

Charles D. Walcott

Discovered the Burgess Shale "fossil-bearing unit"

Burgess Shale

Most popular fossil site of sedimentary rocks containing the best record we have of Cambrian animal fossils, being one of the most diverse and well-preserved fossil localities in the world.