Geologic Time Scale and Stromatolites

What role did cyanobacteria play in Earth’s early atmosphere?

Which statement about stromatolites is true?

Which of the following metals is rare and commonly found in meteorites?

What event is marked by the presence of iridium bands at the K-T boundary?

During which eon did the majority of Earth's history occur before complex life emerged?

Which of the following statements about the Mesozoic Era is correct?

What characteristic of iridium makes it suitable for applications like satellites and spark plugs?

Which statement about the Phanerozoic Eon is true?

Stromatolites

Structures formed by cyanobacteria
Layered due to the activity of cyanobacteria
Cyanobacteria are photosynthetic, producing energy from sunlight
Cyanobacteria have tough, multilayered cell walls that aid in fossilization
Cyanobacteria played a key role in raising atmospheric oxygen levels during Earth's early history

Geologic Time Scale

Precambrian: 4.5 billion years ago (bya) to 550 million years ago (mya)
- Includes Hadean, Archean, and Proterozoic Eons
- Represents the majority of Earth's history before complex life
Phanerozoic Eon
- Paleozoic Era: 550 mya to 250 mya
  - Began with the Cambrian Explosion, leading to rapid diversification of life
  - Includes Cambrian, Ordovician, Devonian, Carboniferous, and Permian periods
  - Ended with the Permian Extinction, causing the loss of 95% of species
- Mesozoic Era: 250 mya to 65 mya
  - Dominated by dinosaurs
  - Periods include Triassic, Jurassic, and Cretaceous
  - Ended with the K-T Extinction, resulting in the loss of 80% of species, including dinosaurs
- Cenozoic Era: 65 mya to present
  - Includes Paleogene, Neogene, and Quaternary periods
  - Marked by the rise of mammals and the development of human life

Iridium

Found in bands at certain extinction event boundaries, like the K-T boundary
Rare metal on Earth but common in meteorites
Highly dense, resistant to erosion, and can withstand high temperatures (up to 2,000°C)
Used in satellites, spark plugs, and decorative items due to its durability and rarity

Explore the fascinating world of stromatolites and their formation by cyanobacteria, which played a crucial role in Earth's early history. This quiz also covers the Geologic Time Scale, detailing the major eons and eras, including Precambrian and Phanerozoic times. Test your knowledge about the evolution of life and the significant events that shaped our planet.