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
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?
If you’re a structural geologist or geology student in the midcontinent region, you’ve most likely made the pilgrimage to Van Hise Rock. Located near Rock Springs, Wis., in the Baraboo quartzite range, Van Hise Rock is among the best-known structural geology landmarks in the Midwest. Van Hise Rock provides spectacular exposure of the nearly vertical… Continue reading Van Hise Rock
Here’s some lovely cross bedding in the ~1.7 Ga quartzite from Baraboo, WI!