You know those cool trilobite fossils? Turns out you can dig ’em up in limestone and shale deposits in places like Ohio, Indiana, Pennsylvania, and New York. A recent speaker at the Northeast Georgia Mineral Society later heard about a limestone cement quarry in Ohio that was just packed with Devonian period goodies – trilobites, shark bits, shellfish, and brachiopods in their gravel. The catch? Whole trilobites were super rare, and finding one was like hitting the jackpot. It actually took him a good three or four trips to the quarry before he finally snagged a complete one.
Fast forward a bit, and when he was at Cleveland State University, he and his buddies went fossil hunting. He and a college friend actually found a bigger one, but, oops, it broke in half! So they each took a piece. And get this – as they were heading out, one of their other friends, who wasn’t even that into fossils, just happened to spot a whole one right near where they parked. Talk about luck!
Now, for a quick geology lesson: Trilobites are these extinct arthropods that had cool exoskeletons and jointed appendages. Think of them as ancient relatives to modern-day crabs, centipedes, spiders, scorpions, ticks, horseshoe crabs, spiny lobsters, and even those little rolly-pollys you find in your garden. Their name, “trilobite,” makes sense when you see them, because the fossil has three main sections: a central spine and two lobes on each side. Trilobites had compound eyes and were ocean dwellers. Scientists figure out what they ate based on their mouthparts – some were probably plant-eaters, while others might have been predators. There are a whopping 22,000 known species of these guys!
Trilobites eventually disappeared during the Permian period, likely due to a massive die-off, possibly from a meteor impact that caused global chaos and volcanic activity. Plus, some folks think another arthropod, the Anomalocaris, might have been preying on them.
Our fine speaker even found some complete specimens in the shale deposits of the Conasauga River in NW Georgia once. It was near a new neighborhood, and he found tons of different species! But, sadly, word got out, and collectors started parking all over the neighborhood, which led to the site getting shut down and blocked off. It’s a real reminder for collectors to always be super respectful of these awesome locations. Oh, and if you’re looking for more trilobites, you might have some luck in Tennessee and Kentucky, too! Enjoy these photos of trilobites fossils from Georgia and from Madagascar, and enjoy the educational slides and feel free to share!
From our recent new homebase in North Georgia, let’s talk about the Blue Ridge and the Piedmont lands and the geology and minerals of North Georgia. We’ll look at them together, seeing as how the rocks there, the ones that got squeezed and heated up (that’s metamorphic, you know) and the ones that bubbled up from the earth like old volcanoes (igneous), well, they’re cut from pretty much the same cloth.
Now, the old-timers figure that way back yonder, the whole shebang of North America bumped right into this big ol’ landmass called Gondwana, and that’s how they got Pangea, this super-duper continent. That mighty clashing of the earth’s plates, it caused all sorts of cracks and wrinkles in the Blue Ridge and Piedmont here in Georgia. And all that pressure and heat? Why, it just folded and lifted those rocks right up.
The Blue Ridge Mountains, bless their hearts, they’re some of the ancientest hills you ever did see, a whole lot older than those young whippersnappers out west, the Rockies, and even them big fellas over in Asia, the Himalayas. When the Blue Ridge first poked their heads up, they’d have been some of the tallest things around, I reckon. But then the rains came, and the floods, and they just washed away tons and tons of rock and dirt down into the lowlands, the plateau, and even further out. Some folks who study rocks have even found bits of that old wash way out in Arizona, in the Grand Canyon!
Later on, that Pangea thing, which included these very Appalachian Mountains, well, it got all torn apart by more of that earth movin’ and shakin’. Scientists have found pieces of these same Appalachians way down in South America, over in northwest Africa, and even in Greenland, Great Britain, and Europe. But nowadays, all that’s left standin’ here are the tough old cores of these Appalachian rocks.
Now, up in northeast Georgia, them Blue Ridge Mountains make up the highest ground in the whole state. Here in Georgia, these rounded ridges and worn-down peaks go from about sixteen hundred feet up to nearly forty-seven hundred feet above sea level. The whole Appalachian chain goes even further, roughly from Alabama all the way up to New York.
The Blue Ridge, they’re known for that pretty blue haze that hangs over ’em, and for their mighty steep gorges, canyons, and waterfalls. Take Tallulah Gorge, for instance, down there in northeast Georgia. It’s a good six hundred feet deep, making it the fourth deepest canyon east of them Rocky Mountains. Mighty impressive!
Now, the southern edge of the Blue Ridge is near this thing called the Brevard Fault Line. Right on the other side of that line, you got the Piedmont, and it’s made up of some mighty old rocks too. The story goes that these rocks started out as just plain old muddy clay that settled way down deep in the ocean. Seems like mud gets carried the furthest from land that’s wearin’ away, mixes in with some sand, and then just sinks to the bottom of the deep blue sea. Then, when that mud gets squeezed and heated up (that metamorphism again), it turns into mica. And as most folks around here know, Georgia’s got plenty of that sparkly mica.
The rockhounds have also found a lot of this stuff called Metagraywacke, which is just sandstone that’s been changed by heat and pressure. Graywacke, that’s what they call the stuff before it changes, forms in layers of clay and sand that got sorted out in deep water with strong currents. The bigger bits of gravel and sand sink to the bottom first, and then the finer stuff settles on top. Over time, all that gets cooked and squeezed, and out pops Metagraywacke.
Now, there’s all sorts of different metamorphic rocks and minerals in the Blue Ridge area. That’s ’cause it’s been through a whole bunch of episodes with different amounts of heat and pressure and foldin’. Along the western edge of the Blue Ridge, where things weren’t quite as intense, you find slate and phyllite (some folks call it fillite). Then, as you go further in, you find minerals like chlorite (that forms at around two hundred degrees Fahrenheit), shiny silver muscovite, black biotite, garnets, and staurolite. And over on the eastern side, where things got real hot and squeezed tight, you can find kyanite (that takes about eleven hundred degrees Fahrenheit to form!), sillimanite, andalusite, some pretty zebra-striped gneiss, and even migmatites.
And that ain’t all! We got copper, marble (that used to be limestone, like around Tate), talc, this old blue quartz meta-granite (got its color from titanium), quartzite rings around Tallulah Dome, and even some of that igneous granite in the Blue Ridge. Why, even Mount Yonah over in White County is made of this granitic gneiss. It formed way back when molten granite pushed its way up into layers of metamorphic rock.
Now, one more thing you’ll find in both the metamorphic and igneous rocks of the Blue Ridge and the Piedmont is quartz. It can form when hot, watery stuff full of silica pushes into cracks in the rock and makes veins. And gold? Well, gold can be found in those same kind of veins, along with quartz and some other minerals like pyrite. In fact, if you see quartz veins that are stained with iron, that can be a sign that there might be gold nearby. Them gold deposits in the Blue Ridge led to the first big gold rush in America, right around Dahlonega, Georgia. Read our review of the Dahlonega Gold Museum here: http://www.americangeode.com/blog/dahlonega-gold-rush-museum-review/. You can also find a little bit of gold scattered in those igneous granites, but most of the gold folks have dug up over the years came from what they call placer deposits – that’s just old river and stream gravel that’s been worn away over time.
Remember to #getoutandrockhound and share www.americangeode.com with your rockhound friends!
Since moving back to North Georgia in late 2024, American Geode are loving and appreciating the chances for rockhounding, hiking, and exploring all the geology and geologic wonders of North Georgia. The North Georgia geology is a lot of metamorphic, so while there are few fossils to be found, North Georgia is full of quartz, some garnets, some amethyst and the rare gold discovery in Dahlonega that kicked off the first American Gold Rush and the infamous “Trail of Tears” for the Cherokee Indians (http://www.americangeode.com/blog/dahlonega-gold-rush-museum-review/). One of the benefits and advantage of living in North Georgia are that we are in the middle of dozens of state and federal parks, with plenty of variety for hiking experiences in the mountains.
We recently visited the Charles Smithgall Woods, https://gastateparks.org/SmithgallWoods, for a day hike to see Mount Yonah. The Smithgall Woods were gifted to the state of Georgia by philanthropist Charles Smithgall who also started a dog and cat shelter that American Geode supports, https://charlessmithgallhumanesociety.org/. This hike is just under 2 miles and can be completed in less than an hour unless you stop to smell the Georgia mountain laurel and take selfies in front of one of the best views of Mount Yonah. American Geode hiked the trail called Laurel Ridge Trail, and it was a delight.
The American Geode team hiked it during the week, so the crowds were a little lighter than on the weekends. While rockhounding is technically not permissible, we enjoyed so much admiring the geology of the hike as it descends up and then down a mountain. We took so many pictures and spotted numerous varieties of butterflies and saw a copperhead snake from the distance, whom we did not approach but seeing a copperhead was magnificent and a thrill. Hiking is a great workout, and we look forward to hiking all the trails of Charles Smithgall Woods. See our pictures of Mount Yonah (aka Yonah Mountain around North Georgia) and imagine what a gorgeous landscape you will see depending on the day, weather, and time of year.
Contact American Geode directly for any advice or questions, and enjoy rockhounding North Georgia!
Yonah MountainYonah MountainYonah MountainGeology of Yonah Mountain, North Georgia
American Geode are also paleoart, art, and antiques appraisers, dealers and collectors, and we very recently acquired the entire vintage private artwork collection of PaleoArt that was used in the 2002 calendar of the American Museum of Natural History, New York. The artist who had lived in New York City and worked at the museum, moved to North Georgia, which is also the homebase of American Geode now, and we have had the chance to become friends with her and share our love and appreciation for the museums of New York City, especially the American Museum of Natural History. Here is an article and review about AMNH from our most recent visit: http://www.americangeode.com/blog/tips-for-visiting-the-american-museum-of-natural-history-amnh-in-new-york/
These sketches are preserved under wax paper with the annotations and notes on the wax paper. The paleoart sketches themselves are so charming, educational, and cool; they speak for themselves. We are cataloguing this collection of PaleoArt and will offer it for sale sometime this year.
Please contact American Geode directly if you would like more information. We will also be posting images on social media, https://x.com/AmericanGeode. Below is just a portion of this magnificent special PaleoArt collection.
PaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoart Original Artwork used for the American Museum of Natural History 2002 CalendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendarPaleoArt for the American Museum of Natural History 2002 calendar
We love the American Museum of Natural History; we actually love all the museums of New York City. The American Museum of Natural History, AMNH, contain so much information to be read, observed, viewed and not to be missed, that you may want to devote two days to a visit, but here are a few tips and suggestions that are especially relevant to rockhounds and geology, mineral, and fossil enthusiasts.
The first and we do mean first tip to enjoying your visit to AMNH is to enter on the Columbus Avenue side. Enter on the side opposite, on the other street, on the backside, and do not wait in the long line on the Central Park West main entrance with the pair of lion stone sculptures. That main entrance always has a line that can last up to an hour. On the other side of the museum is another entrance that rarely has a line, and you can walk right in if you pre-paid for your tickets and you can buy your tickets there too. This is a very important trick that you will thank us for once you experience the difference and convenience and ease of entering the museum on the Columbus Ave side.
A benefit of entering the museum on the Columbus Avenue side is that the first major hall and exhibition you enter is the newly remodeled famous Mignone Halls of Gems and Minerals. This is a fascinating gem of an exhibition that contains some of the largest minerals in the world, some of the most rare minerals and fossils in the world, and education and insight throughout. When we were there last, we spent 2 hours just in the area for gems, minerals, and fossils, and then right next door is the equally fascinating insect and bug hall and exhibits where you get to see live insects as well.
So plan your visit wisely fellow rockhound and gem, mineral, fossil enthusiasts, and start your visit to the American Museum of Natural History from the Columbus Ave entrance. Enjoy photos below from our March 2025 visit to New York and contact American Geode with any questions. #NewYorkRocks