Introducing
Your new presentation assistant.
Refine, enhance, and tailor your content, source relevant images, and edit visuals quicker than ever before.
Trending searches
Explain the Snowball Earth hypothesis and the evidence that
11
What is Snowball Earth - context
•The concept of a ‘Snowball Earth’ was first introduced in the 1960s, but it was dismissed originally by scientists of the time
•A Snowball Earth comes about due to feedbacks and tipping points, which will be explained in more detail later on
•Once in a Snowball Earth, it is incredibly hard to get out of with the phenomenon lasting millions, if not tens of millions of years (Revolutions that made the Earth, 2011)
•Temperatures in the poles reached as low as -80℃, and the equator dipping to a chilly -20℃. Comparably the average temperature at the equator nowadays is at least 40℃ warmer (Encyclopedia of the Atmospheric Environment, 2000)
•There are many lines of evidence for a Snowball Earth, but the concept is still disputed today, as academics introduce other possible models as will be discussed later
Past snowball events
- ~2200 Ma (Makganyene)
- ~710 Ma (Sturtian)
- ~640 Ma (Marinoan) (end of the Proterozoic Eon)
Mechanisms and triggers
Alternative hypothesises
Structure
Explain the Snowball Earth hypothesis and the evidence that supports it
Paleomagnetism
•What is Snowball Earth?
•When were Snowball Earths?
•Mechanisms and Triggers
•What can melt a Snowball Earth?
•How do we know Snowball Earth happened?
•The aftermath of Snowball Earth
•Alternative Hypotheses
Carbon isotopes
What can melt a snowball?
Cap Carbonates
Evidence for snowball earth
Dropstones
BIFs
Dropstones are large rocks and boulders that have been carved up from the surface by a mobile glacier, then deposited upon its melt.
Band Iron Fomations are formed from the precipitation of iron in an anoxic environment
They are evidence for a snowball earth because they occur in places now unfeasible for ice growth such as ___
In an oxic environment Fe can exist as soluble ferrous oxide
In an anoxic environment like an ocean blanketed by ice, Fe is precipitated out to its Ferric oxide form