Week 11 Flashcards
Biblical account of apocalypse
described in the Book of Revelation. It tells of a dream-like vision of heaven and the final battle between good and evil, ending with God’s triumph and the world’s end.
What are mass extinctions and how many major ones have occurred?
Mass extinctions are global events where many unrelated species die out in a short geologic time. Earth has experienced five major ones, known as “The Big Five.”
What’s special about the K-T boundary at Gubbio, Italy?
a thin clay layer marks a sudden break in limestone beds—evidence of an abrupt halt in ocean sedimentation and a dramatic fossil change. It’s one of the best records of the Cretaceous-Tertiary extinction.
Other evidence of Bolide Impact
- Shocked quartz
- Tektites
- Soot Particles
- The “fern” spike
Fern spike
A sudden rise in fern spores and drop in tree pollen suggests massive deforestation likely from global wildfires triggered by an asteroid impact. Ferns, being pioneer species, rapidly recolonized the devastated landscape.
What environmental stresses likely affected life before the K-T asteroid impact?
Volcanism – Massive eruptions in India (Deccan Traps) released sulphur dioxide, cooling the climate and stressing ecosystems.
Sea Level Change – Widespread shallow seas during the warm Cretaceous began to recede, altering habitats and ecosystems.
What were the effects of falling sea levels at the end of the Cretaceous?
Loss of shallow seas → extinction of many marine species
Exposure of continental shelves → more arid conditions on land
Land bridges formed → migration, increased competition, and spread of disease among land animals
NASA’s deep impact mission
Sent a spacecraft to comet Tempel 1 and smashed a 370 kg copper mass into it. Helped scientists understand what might happen if a comet struck Earth
Scientific Concepts in The Core: Accuracy vs. Fiction
✅ Accurate:
Earth’s magnetic field is generated by convection in the liquid outer core.
The magnetic field fluctuates and reverses polarity (last flip ~780,000 years ago).
❌ Flawed:
The magnetic field is driven by convection, not core spin.
A ship made of “unobtainium” surviving extreme conditions is unrealistic.
Giant crystal caverns in the mantle are impossible under high pressure.
The Earth’s Magnetic Field & Microwaves: Myths vs. Reality
❌ Misconception in The Core
Earth’s magnetic field does not block solar microwaves. The atmosphere does.
✅ Reality:
If the magnetic field shut down, the atmosphere would still protect us from harmful radiation.
Communication systems might be affected, but no biological catastrophes have been linked to magnetic field reversals.
Thermohaline Circulation
Driven by temperature & salinity differences in the ocean.
Warm water (like the Gulf Stream) flows north, cools, becomes denser, and flows south, warming regions like Western Europe.
Could Thermohaline Circulation Shut Off?
Yes! Global warming decreases temperature differences between the poles and tropics.
Freshwater from melting ice caps reduces density, blocking the circulation.
Effect of Shutting Off Thermohaline Circulation
Eastern North America & Scandinavia would get colder, tropics would heat up.
Changes would occur over decades, not days.
Highlights the urgency of addressing global warming.
