Do you ever see pictures of beautiful geology all over the world and think “WOW, I don’t think I’ll ever be able to see that in person”? Well, think again. This post is dedicated to helping you find amazing geological finds in a place I can guarantee you will visit just about every day: the bathroom (and no, I’m not just talking about coprolites)!

The goal of this post is to teach you a little about the types of rocks you might see the next time you’re in a restaurant bathroom, a bathroom at the beach, the library bathroom, or even the bathroom in your own house! You might be thinking “oh, but what can I learn from a bathroom?!” Well, you just might be surprised. So, let’s get to learning!

Our first stop is a small restaurant in Richmond, Virginia. The food was good, but the real treat was finding the granite countertops inside the bathroom (Figure 1)! Take a look! Granite is an intrusive igneous rock: meaning, the magma from which the rock was made cooled slowly underground. We know this because of the very large crystals that we can see! Crystals grow from the liquid magma; the longer they take to cool, the larger they grow. Now, let’s look more closely at these big crystals. If you look at the large, light pink colored crystals where my finger is pointing you might see that they are what we call “zoned”- meaning, there are alternating circles of slightly different colors inside the crystals- their rounded shape means we’d assign the term “concentric zoning” to them. This actually tells us something really cool about their cooling temperature!

Magma cools at different rates- depending on where it is on Earth or the types of materials from which the magma is made. This rate of cooling determines how and when certain minerals form, or crystallize. In other words, geologists know quite well at what temperature a mineral will form within a magma chamber as it cools down. This predictable pattern of mineral formation with cooling temperatures is called Bowen’s Reaction Series (Figure 2). When this happens, it means the chemistry of the still-liquid magma changes quite a bit!
To put this into a more delicious and more relatable example, think about a giant jar of Starburst-with red, pink, yellow, and orange evenly mixed in. Let’s say you give this jar to me (I really love Starburst). I will preferentially eat all of the orange ones out of it; then the pink; then the red; and finally, we’ll only be left with yellow (gross, who eats the yellow ones?!). We’ve changed the overall composition of the magma (i.e., the jar of Starburst) by preferentially pulling out one type of material in a specific pattern. Now, take a look at the giant crystal my finger is pointing to- the zoning is going back and forth between a sodium and a calcium rich solution in the feldspar (the name of the mineral)-this indicates that the temperature of the magma where this was cooling was changing slightly, alternating between a little hotter and a little cooler.

Now granite is really cool and it’s a very common bathroom countertop, so let’s look at another example (Figure 3)! This granite was part of a larger piece of rock that was installed in a private home bathroom in Fayetteville, North Carolina. This little piece was leftover, so the countertop store let me have it! This granite is similar to the granite from above, but it doesn’t have any zoning, meaning it all cooled without any weird changes in temperature. However, it does have one pretty cool feature-the garnets! These garnets (the little red crystals) are of the almandine variety. Almandine is a type of garnet that has a lot of iron and aluminum in it. Garnet forms in granite as an accessory mineral (meaning, not a major component) and different garnets can mean different things. In this particular sample, this almandine garnet means the magma was aluminous; meaning, there was a lot of aluminum in this magma!

I found this gem at a women’s bathroom in the San Francisco airport (SFX) last year (Figure 4)! This rock is called a migmatite. A migmatite is unique in that it is a cross between an igneous (formed directly from cooled magma or lava) and a metamorphic rock (a rock that was exposed to heat and pressure after its original formation). The dark and the light material you see here are from two totally different processes. The light material here is mostly quartz (the same mineral that we call amethyst or rose quartz–quartz occurs in a variety of colors). The lighter material is much more viscous-meaning, it resists flowing (like honey or molasses), while the darker stuff (primarily from minerals called pyroxene or hornblende) has a lower viscosity and flows more easily. Now, do you see how the light colored material exhibits small and irregular folds? These folds are what geologists call “ptygmatic”. These ptygmatic folds generally occur at pretty high temperatures and pressure; these variables cause the layers to fold and buckle the way that they do because of the differences in viscosity. The high temperature and pressure, along with the high viscosity of the light material, will cause these types of folds to form (these are also known as “passive folds”).

I recently saw this one (Figure 5) at the St. Petersburg beach in Florida, pretty close to where I live. These blocks are part of the public bathroom walls and as you can see, these bathroom walls are chock full of fossils! Wow! These fossils are from Florida and they’re pretty recent–no more than 10-20 million years old. They’re also primarily mollusks, the large group that contains octopuses, clams, snails, and oysters. Imaged here are snail fossils-you can identify these snails by their long, delicate shells- and clam fossils-you can identify those by the much larger shells that have ridges along the edges. These types of fossils are called “molds”-this means that the shell itself has been worn away and all that’s left is the sediment that either filled in the shell or the sediment that formed around the shell. The internal molds are where you can see an actual 3D shape of the inside of the shell, whereas the external molds are where you only see an impression of the shell.

Last but not least, my mom snapped this picture of her bathroom just for this post (thanks, Mom!)! Labradorite is a beautiful mineral-it’s a type of feldspar, which is in the same group as the lovely pink minerals seen in the granite in Figure 1. What makes labradorite so different, though, is that this feldspar doesn’t form in granite-it forms in a very different type of rock, like basalt! Basalt is an extrusive igneous rocks, so it forms from lava that cools at the Earth’s surface. Basalt is found in places like Hawaii, where it comes out of volcanoes, or at mid-ocean ridges, where new seafloor is being made. Basalt is mafic, meaning that it is full of heavy minerals like iron and magnesium. Labradorite is famous for its iridescent sheen-you can see it here in Figure 6!

I hope that this post has shown you that you don’t need to travel to fancy and far away locations to see real and beautiful geology up close. Sometimes, interesting geology can be as close as the nearest bathroom! Next time you see one of these counters, stop and take a look! What do you see? Do you see fossils? Garnets? Zoning? Do you see something entirely different? Before I go, I’d like to thank geologists Cameron Hughes, Zachary Atlas, Elisabeth Gallant, and Jeffery Ryan for help with identifying some of the details in these rock samples!

This is the final post in the series of the geology of Maine and the Bay of Fundy. To recap for those of you who might not have read my first post, I documented all the geology I saw recently on a vacation my husband and I took to Maine and New Brunswick, Canada. This is the second post all about the geology of the Bay of Fundy! This one, though, will talk about the famous rocks of the bay and how they got the unusual shapes that made them famous. Remember, the Bay of Fundy is famous because it has the highest tides on Earth.

So what do these tides do to the rocks? To answer this, let’s first go to St. Martin, to the famous Sea Caves. You might be looking at this first image and think “what caves!”? Well, this first image is taken at high tide, so the caves are almost entirely underwater. High and low tide were separated by about six hours, so we saw high tide, admired the lovely scenery, and drove to see the Fundy Trail Parkway, a park that you can drive or hike the entire way through for some GORGEOUS scenery. There are spots to pull over and get out, hike short distances, or just look out from a cliff to see some beautiful sites. Here’s a picture overlooking the Bay of Fundy – remember, these lovely coastlines were largely created by the formation, movement, and melting of glaciers.

We returned to the Sea Caves to see it at low tide-take a look! This picture is from the SAME spot, give or take a few feet. This photo should show you the height and amount of water moved by tides every day in the Bay of Fundy. The presence of these caves is due to mechanical weathering-literally, the waves associated with the tides coming in and out are quite strong and they break down the rocks. Thousands of years of these waves have created immense caves and crevasses. Once you are able to walk across the seafloor at low tide, you can truly appreciate just how incredibly large these caves are and just how strong the tides are! Here’s an image of me inside one of the caves!

There’s one last thing I want to point out about these tides-the effect that they have on living creatures! Snails and barnacles live in high abundance all over the area affected by low tide and these creatures find incredible ways to survive when the low tide means that they aren’t covered by water! Snails will gather in small cracks in rocks where water will pool; barnacles will form more in shadier areas, so the rocks will remain more damp than those exposed to the sun. Sometimes, snails will hang on to a piece of algae just to survive until the water comes back! Check out this image of a snail holding on for dear life!

Now, let’s travel north to Hopewell Park, where the most famous rocks from the Bay of Fundy are. First, let’s look at the difference between low and high tide. These images are taken just about 4 hours apart. So the rock you see here was broken off from the cliffs due to chemical weathering-water percolating through cracks and breaking them apart. But, the odd shape that you see now, where the rock is much narrower on the bottom-that’s due to mechanical weathering. Wave action over thousands of years has caused these shapes to form. These rocks CAN fall without warning (and have, even recently), so park rangers are always making sure to look for signs of instability.

To really experience high tide, my husband and I signed up to kayak through these rocks. To say that the waves here were strong is an understatement! The waves were cresting at just under 4ft-so imagine sitting down on the beach front-you’d be completely covered (if you were curious, kayaking in 4ft waves and high winds was a blast, but also a little terrifying!)! Here’s an up close picture of that same rock you saw in the previous two pictures, from the kayak! Now you can really see where the rock is narrowed at the base-the line between the narrow and wider part of the rock marks the highest the tides can go.

I hope you’ve enjoyed this series! I think one of the most important things I can say here is that this trip made me rediscover my love of geology. Sometimes, when you work long hours every day as a geologist, it can become a little hard to remember just why you love it. If you’re feeling that way, I encourage you to get out and go explore for a little while- a few hours, or even a few months, if you can!

Sarah here –

This post is a continuation of my first post, the geology of Acadia National Park. To recap for those of you who might not have read my first post, I documented all the geology I saw recently on a vacation my husband and I took to Maine and New Brunswick, Canada. This post will be all about the geology of the Bay of Fundy! Specifically, this will be about how glaciers have shaped the geology of the area.

The Bay of Fundy is an incredibly famous geologic area for a good reason-it has the highest tides on Earth, with the highest reaching nearly 56ft! The reason why the tides are so high here has to deal with the shape of the bay-the bay narrows quite a bit (as you can see from the map), so as all the water enters the bay, it’s forced to stack up on top of each other, making the tides reach these incredible heights.

Glaciers have shaped a lot of the geology along the Bay of Fundy; as glaciers advance and retreat, they leave telltale signs. One of the best signs are when you see rocks called tillites. These rocks are made of glacial sediment. They’re fairly easy to recognize-often, you’ll see rocks with very large, poorly sorted clasts (meaning, all kinds of different sizes of sediment). These are left behind by glaciers! Here is an example of tillite along the coast of the Bay of Fundy. Look at all of the different sizes of clasts in there! This rock was found at the Irving Nature Center, St. John, New Brunswick. The wave energy in this particular area is very high, which you can tell by the lack of small sand grains and the prevalence of much larger clasts (pebbles-boulders). Another sign of glacial activity is the presence of striations on rocks. Striations are scratches in rocks that are caused by glacial ice moving over them. These glaciers can have lots of rock and sand debris within it, so as they move over rocks, it can cause a lot of surface damage to the rock. Check out this picture of striations on volcanic rocks, also from the Irving Nature Park!

Arguably, the most famous area of the Bay of Fundy is the site called Hopewell Rocks. I’ll discuss a lot more about the Hopewell Rocks in my final post, but for now, let’s talk about how glaciers shaped these famous rocks. As glaciers last retreated from these areas (meaning, the Earth warmed and glacial ice melted), the water from the glaciers filled into the ground and caused cracks to form along the coast. This is called chemical weathering. Water is a chemical and it’s the most common chemical that rocks come into contact with when we’re talking about chemical weathering. These cracks eventually caused these large rocks to be separated from the cliff line. This phenomenon might be more familiar to you when you’re driving- when roads (in colder areas, especially) have small cracks in them and water gets into those small cracks, that water can freeze, causing the crack to expand. After multiple rounds of freezing and melting, these cracks become a real problem to drivers!

During our next (and final) piece about my trip through the Bay of Fundy, we’ll look at how these famous rocks are shaped by mechanical weathering, instead of chemical!

Sarah here –

I recently went on a trip with my husband to Maine, USA and New Brunswick, Canada to see some of the best geology these places had to offer! I’ll be showing you a lot of the gorgeous geology (and some cool biology!) through a series of posts. This first post will be all about my trip to Acadia National Park. My husband and I hiked quite a few trails (about 20 miles of trails total!) in the four days we were there and we learned quite a lot about the geology of the park from our adventures.

A lot of the rock you’ll see in the popular parts of Acadia- especially the trails in the main part of the park-will be granite. Granite is an igneous rock that formed intrusively, meaning, it formed under the surface of Earth. You can generally tell whether igneous rocks formed intrusively or extrusively (on Earth’s surface), because the sizes of the grains will be different. The magma that makes up granite cools very slowly under the surface of Earth-the slower it cools, the larger the crystals are! But, I digress. Many of the mountains in the Acadian region are made of granite. This granite was formed when two continents- Laurentia (North America) and Avalonia (eastern North America and western Great Britain) slammed together hundreds of millions of years together. When they collided, it forced a huge amount of magma to pool, creating the famous granite we see today (you can read a lot more about the creation of Acadian rocks at this site)! Here’s a photo of me climbing some of this granite on the Beehive Trail! The mountain is very steep and the trails are very narrow, so it is most safely climbed using metal ladders!

Granite is a very hard, stable rock. What that means is that it doesn’t weather away easily, like other rocks (think of how marble gravestones look like after a few decades-marble is much more easily worn down!) But after millions of years, even the toughest of rocks can start to be broken down! Take a look at these rocks here-you can see the cracks from being weathered (likely by rain!)-these cracks allow rain to penetrate into the rock and break it down even faster! To put it into perspective, think of a windshield-if you put a single crack into it, you’ve weakened the glass and further pressure can result in faster spreading of the break. Rocks respond similarly after the first cracks are formed!

I want to show you some of the cool pictures from the other side of Acadia now. This is a lesser known, but just as beautiful part of the park as the most well known part of Acadia. This area is called Schoodic Point. This is also dominated by the same gorgeous granite-but it’s got something else going on that’s really spectacular. If you take a look, you’ll see the gorgeous light colored granite…but also, intrusions of a dark colored igneous rock (called a diabase); this diabase has tiny crystals-meaning, it cooled quickly! We can tell that the dark colored rock intruded into the granite because of the Principle of Cross Cutting Relationships; this geologic principle means that if a rock “cuts across” another rock, the rock that is cutting across is younger (read more about geologic principles here).

So, with that in mind, these diabase intrusions are the remnants of later episodes of volcanic activity. There are multiple episodes of volcanic activity represented here-many of the intrusions are cut by even more intrusions! What a beautiful place. So even though this is a post about geology, I wanted to show you a little bit of the life here at Schoodic Point-the wave activity at this area is VERY high (one easy way to see that is that there’s very little sand at this coast-the wave energy is too high, so the sand gets washed away). The water crashes up onto the granite and some water will stay up there, giving a perfect spot for lots of little critters to form a home! Take a look at this small pool of water-how many critters can you see?

Stay tuned for more posts on the rest of my trip!