Glgy 475, lecture 7

What is the evidence for primitive life existing 2.5 and 3.5 billion years ago?

Archean stromatolites and other ancient microfossils

What is the definition of half life?

Half life is the time needed for half the parent isotopes to decay into the daughter product.

What type of temporal resolution is found in tree rings, ice cores and lake sediments?

High resolution

The archives for global change for continents are...

Lake Sediments and Speleothems

Does he geological record support the scenario of a frozen planet?

No- sedimentary rocks which are 3.9 billion years old have been found in Greenland. There is evidence that primitive life was abundant more than 3.2 billion years ago

Evaporates act as an archive of global change for...

Oceans

How does the accumulation of sediments differ in lakes and deep parts of the ocean?

Sedimentation rates in lakes are fast while sedimentation rates in the deep ocean are very slow.

What is the major archive for studying long-term environmental and climatic change?

Sediments

Give an example of the long time scale that the carbon cycle can operate by.

The carbon fluxes that take place in the transportation of dissolved inorganic carbon from rivers to the ocean cause slow changes.

Give an example of the short time scale that the carbon cycle can operate by.

The carbon fluxes that take place in volcanism cause rapid changes.

What is the the faint young Sun paradox?

There is a contradiction between observations of liquid water early in the Earth's history and the fact that in Earth's early history the sun would have only been producing 70% of the radiation that it produces today. 70% of the current solar radiation would not have been enough to maintain liquid water on earth.

The ---- is one of the smallest carbon reservoirs and hence most susceptible to change.

atmosphere

Provide four examples of geological proxys of climatic and environmental change?

coals, evaporites, tillites, dropstones

Provide two examples of biotic proxys of climatic and environmental change?

fossils, pollen

What are the preferable features of a climate record.

long, continuous and datable

Most of the temperature difference between Venus and Earth can be explained by....

the higher content of CO2 in Venus's atmosphere.