Key Questions about the Early Earth

These questions pose some of the great mysteries of the early formation of our planet and present wonderful opportunities for teaching about the process of science.

Understanding the early Earth presents some unique challenges for teaching Earth science. The geologic record is mostly missing, we're looking through "deep time," and there is no guarantee that Earth processes operated by the same mechanisms or rates as those observed today (the present may not be the key to the distant past). The compositions of the crust, oceans and atmospheres have evolved over geologic time, and the genesis and evolution of life has had a profound effect on the operation of the Earth system. As a result, many competing models have emerged regarding the early history of the Earth. This provides a very rich intellectual environment to train young scientists.

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Jump to key questions about the early earth:

This material was contributed by participants in the 2007 workshop on Teaching About the Early Earth. A related list of questions and answers was developed in preparation for the workshop and can be viewed on the workshop questions page.

• What is the age of the Earth?
• How do we extrapolate backward to understand the conditions of the Hadaean Earth?
• Why is Earth among all terrestrial bodies in the solar system (e.g. Moon Mars Venus and meteorites) the only body to have sialic crust?
• When and how did the continental crust form?
• When did plate tectonics begin?
• The Jack Hills zircons are the oldest materials on earth. What can we learn from them?
• When did oceans form on Earth? What evidence is preserved in the rock record?
• What was the nature of the pre-biotic terrestrial atmosphere?
• What is our current understanding about the origin of the atmosphere?
• What do banded iron formation deposits reveal about the evolution of the atmosphere?
• Is the early evolution of life on Earth the key to resolving the Faint Young Sun paradox?
• Does the low diversity of microfossils in Archean sedimentary rocks reflect a low diversity of microbial life in the Archean?