Second, the Joides Resolution blog (the Joides Resolution is an ocean sediment coring vessel) has a series of posts (1, 2, 3) on geologic thin sections. Not surprisingly, the thin sections pictured are from rocks such as gabbros or sheeted dikes, which are expected in oceanic crust and in ophiolites (oceanic crust exposed on land). There’s a great exposure of the Coast Range Ophiolite just west of Patterson, CA, in Del Puerto Canyon, which is described in a recent blog post by Garry Hayes.
Exploring other worlds up close, and which are different from our own, can be very informative. We may have theories about the composition of worlds like Pluto, of how it formed, how it behaves, and what its surface is like. However, it is not until we go there that we can truly test those hypotheses. In many cases, when we are dealing with worlds vastly different from our own, what we find is surprising, mysterious, and awe-inspiring.
For instance, most pre-New Horizons models would have made Pluto out to be a fairly heavily cratered object, not unlike the Moon. However, that was not at all what was found. The first high-resolution picture released during the flyby, part of a mosaic which is still being put together, had no craters visible. None.
Given that the history of Pluto is likely to have included significant bombardment by smaller objects, this result makes us rethink our model of the processes happening on Pluto’s surface. From what we know of the frequency of impacts, these surfaces would need to have been recently (geologically speaking, so in the last ~100 Ma) formed, eroded, or otherwise modified.
It is encounters like this which help us understand and consider our models, and to recognize which properties of large rocky bodies are important under which circumstances. What is reshaping Pluto’s surface? How did the various terrains form? Do they happen elsewhere? Where does the energy for these processes come from?
Exploring other worlds keeps our thinking fresh, challenges our assumptions, and inspires us to create new models and experiments to better understand our solar system and our own Earth.