Science on Tap: What Do Rocks Teach Us About the Earth?

How do scientists study rocks? What does that teach us about the Earth? On Thursday, June 27, 2024, Rising Silo Brewery hosted the Science on Tap event, “Reading the Rocks: What rocks tell us about the history of the Earth, in the NRV and beyond!” The presentation helped participants understand the answers to these questions. Virginia Tech Department of Geosciences graduate researcher (and Science on Tap organizer) Amy Hagen was the speaker for this month’s event. Hagen led participants through an activity that allowed groups of audience members to categorize rocks by where they formed and how. Participants were able to hypothesize where the rocks may have formed by observing the cracks and ripples in the rock, as well as the grains and sediments that create its structure.

    Groups at tables were given a rock labeled with a letter and a photo of a “thin section,” a magnified view of the rock's structure. A thin section is a thinly cut rectangle of rock that is polished and added to a glass slide. These thin sections help geochemists study the fabric of rocks. Pictured above is an ooid and fossil grainstone. Ooids are tiny round grains that form in places like the Bahamas and the Great Salt Lake.

    Participants were given plenty of time to discuss with their groups about their hypothesis. Pictured above is a mudstone, identified by the mud cracks and ripples. This forms in the tidal zone where waves shape the sediment into ripples and low tide can dry it out and make it crack.

    One family brought a hand magnifier to help them observe smaller features that can help identify the rock. Pictured above is a stromatolite, formed by a buildup of sediment created by microbes. 

    Collaboration was key to forming a hypothesis about where the rock may have been formed. This group was looking at a quartz sandstone, which is formed from white quartz commonly found on the beach.

    Participants had to study each rock sample closely to assess formations that made up the rock. Pictured above is a flat pebble conglomerate, formed when sediment deposits in an area below ocean waves and becomes slightly hardened before a storm comes along and rips it into chunks that then lump together to form a new rock.

    Thank you Amy Hagen and Rising Silo Brewery! Science on Tap is a monthly event sponsored and supported by the Center for Communicating Science and by Virginia Tech's chapter of Sigma Xi.

    By Elliott Byrd, Center for Communicating Science student intern.