An unconformity is an erosional or non-depositional gap in the geologic record. They typically form when an older layer is subject to a period of erosion before the deposition of new sediments. This road cut near Payson, Arizona shows a pretty cool unconformity. Can you find where it is? Check the jump below to see… Continue reading Can you find the unconformity?
Ever wondered why the rocks of Sedona are so vibrantly red? I made this video for Arizona State University’s Science Showcase competition, I’d greatly appreciate anyone who can view/share! Plus learning about geology is fun! (Source: https://www.youtube.com/)
Despite its location in the heart of Wisconsin, the Wisconsin Dells is today known as the “Waterpark Capital of the World.” However, it was its rocks—the actual Dells—that first made it a popular Midwest tourist destination back in the 1800s. The Wisconsin Dells—which come from the French word dalles, or narrows—is a 5 mile stretch of… Continue reading The Wisconsin Dells | An Ice Age and modern water park
Unconformities—erosional or non-depositional gaps—are abound in the geologic record. These erosional surfaces separate a lower, older strata from a younger, upper one (unless the sequence has been overturned). An unconfomity will typically form when an older layer is subject to a period of erosion before the deposition of new sediments. For example, the “Great Unconformity” of… Continue reading Types of unconformities
If you’ve ever looked through clear waters at a beach or gentle flowing river to the sand below, you’ve likely seen ripple marks formed by the moving water. The image above actually shows preserved “fossil” ripple marks in the 1.7 billion-year-old Baraboo (Wisconsin) quartzite. These ripple marks were formed when the marine sandstone was initially deposited… Continue reading Ripple Marks
Does it ever feel like geologists are speaking a different language? With so many different terms to describe and categorize rocks, learning the lexicon of a geologist can be a bit daunting. To help learn some basic geo lingo, here’s a (far from comprehensive) guide of some of the most important classification and terms geologists… Continue reading Geo Lingo | The Language of Geologists
While these dark gray spherical clasts could be mistaken for some type of fossil, they’re actually ooids, which are chemically precipitated sedimentary grains. Ooids form around a nucleus of a mineral grain or shell fragment. Concentric layers composed of calcium carbonate precipitate out and progressively coat the nucleus, forming a pattern almost like tree rings.… Continue reading Ooids • Sedimentary Spheres
This piece of glaciated breccia from the Brussels Hill meteorite impact structure in Brussels, Wisconsin is probably one of my favorites in my collection. It’s not the oldest, nor is it necessarily the prettiest, but it holds one of the best stories. This rock began its life ~440 million years ago during the Silurian Period.… Continue reading Glaciated breccia: A three-part rock story
When compared to many igneous and metamorphic rocks, sedimentary rocks often aren’t the most visually stunning. However, you’ll be hard pressed to find more vibrant and beautiful rocks than the sedimentary rocks exposed at Sedona, Arizona. Rather than the standard hues of gray or beige, these sandstones, limestones and shales are breathtakingly vibrant shades of… Continue reading The Red Rocks of Sedona, Arizona
This photo displays a pretty spectacular unconformity—an erosional/non-depositional surface where rock units deposited during different intervals of time appear to be continuous. In the bottom half of the image, you can see Paleoproterozoic pink quartzite ~1.7 Ga in age, while in the top half of the image—directly overlying the quartzite—is Cambrian sandstone conglomerate ~540 Ma… Continue reading Can you spot the unconformity?