Doing the “sting ray shuffle” through the shallow waters of the estuary of a small stream and the Mississippi Sound, we used dip nets to collect organisms from the sediment-water interface.
We found mostly invertebrates. There were lots of small white crabs. Most, but not all, were too small to pinch.
We also grabbed quite a number of translucent shrimp.
You can very clearly see the entire gastro-intestinal system of this small shrimp.
And there were a lot of hermit crabs.
An understandably shy hermit crab.
A couple students also picked up some small snakes, but they quickly slipped through the dip net’s mesh and escaped.
Simple and effective, dip netting was a nice way to start the Coastal Sciences Camp.
As you may have guessed from the previous posts about waterspouts and the dolphin, we’ve been on the Gulf coast for the last few days. Specifically, we were visiting the Gulf Coast Research Lab‘s Marine Education Center for two days for our end-of-year trip.
It was excellent. The weather was perfect; sunny with lots of cumuliform clouds for shade but little rain. However, the what really made the trip work was that we had a good, interesting, and varied program, directed by an excellent instructor, Stephanie T..
Stephanie T. pointing out the finer points of piscine morphology.
After lunch, we spent some time in their classroom identifying organisms we’d collected in the morning, dissecting squid, and having an overview of the geography of the region.
We weren’t looking for them at the time, and later when we were looking for them we didn’t find them, but on our trip back to the GCRL-MEC a dolphin decided it wanted to play in our boat’s wake.
It would jump through the face of the bow wave. Usually horizontally, but vertically once or twice.
Playing.
Dolphins usually travel in pods of up to a dozen or so individuals. This one, however, was alone. We’d seen it earlier, while we were walking on the beach and picking up trash. The dolphin may have been playing or eating, but it was certainly scaring the small fish. A couple birds took advantage of this to make their own catches, with near vertical dives into the gently rolling waters of the sound.
It was wonderful to observe.
Bird caught in the middle of a dive, just before it splashed into the water.
As we waded through the Mississippi Sound, doing the Sting Ray Shuffle, sampling for benthic fauna, we came across these two waterspouts. Our guide, Stephanie, from the Gulf Coast Research Lab’s Marine Education Center, said they’re not that common.
The first thing you notice is a small, rickety bridge whose main job is to keep your feet dry as you cross a very small stream. The stream is on its delta, so the ground is very soggy, and the channel is just about start its many bifurcations into distributaries that fan out and create the characteristic deltaic shape.
Delta and estuary of the small stream near the villas.
There’s a bright orange flocculate on the quieter parts of the stream bed. It’s the color of fresh rust, which leads me to suspect it’s some sort of iron precipitate.
It is quite easy to stick your finger into the red precipitate at the bottom of the stream.
Iron minerals in the sediments and bedrock of the watershed are dissolved by groundwater, but when that water discharges into the stream it becomes oxygenated as air mixes in. The dissolved iron reacts with the oxygen to create the fine orange precipitate. Sometimes, the chemical reaction is abiotic, other times it’s aided by bacteria (Kadlec and Wallace, 2009).
The bark has been chewed off the top half of this stick. The tooth marks are characteristic of beavers.
Past the small delta, the trail follows the lake as it curves around into another, much bigger estuary (see map above). We found much evidence of flora and fauna, including signs of beavers.
We even took the time to toss some sticks into the water to watch the waves. With a single stick, you can see the wave dissipate as it expands, much like I tried to model for the height of a tsunami. We also threw in multiple sticks to create interference patterns.
Observing interference patterns in waves.
The Oak Ridge Trail, which we followed, diverges from the somewhat longer Pin Oak Trail at the large estuary (which is marked on the map). The Pin Oak Trail takes you through some beautiful stands of conifers, offering the chance to talk about different ecological communities, but we did not have the time to see both trails.
Instead, we followed the Oak Ridge Trail up the ridge (through one small stand of pines) until it met the road. The road is on the other side of the watershed divide. I emphasized the concept by having my students stand in a line across the divide and point in the direction of that a drop of water, rolling across the ground, would flow.
At the watershed divide.
Then I told them that we’d get back by following our fictitious water droplet off the ridge into the valley. And we did, traipsing through the leaf-carpeted woods.
Students imitating water droplets find a dry gully.
Of course there were no water droplets flowing across the surface. Unless its actively raining, water tends to sink down into the soil and flow through the ground until it gets to the bottom of the valley, where it emerges as springs. Even before you see the first spring, though, you can see the gullies carved by overland flow during storms.
Spring.
Following the small stream was quite enjoyable. It was small enough to jump across, and there were some places where the stream had bored short sections of tunnels beneath its bed.
The stream pipes beneath its bed. Jumping up and down over the pipe caused sediment to be expelled at the mouth of the tunnel.
I took the time to observe the beautiful moss that maintained the banks of the stream. Students took the time to observe the environment.
Taking a break at the confluence of two streams.
Downstream the valley got wider and wider, and the stream cut deeper and deeper into the valley floor, but even the small stream sought to meander back and forth, creating beautiful little point bars and cut-banks.
A small, meandering channel. Note the sandy point bars on the inside of the bend, and the overhanging cut-banks on the outside of the curve.
As the stream approached its estuary it would stagnate in places. There, buried leaves and organic matter would decay under the sediment and water in anoxic conditions, rendering their oils and producing natural gas. We’re going to be talking about global warming and the carbon cycle next week so I was quite enthused when students pointed out the sheen of oils glistening on isolated pools of stagnant water.
The breakdown of buried organic matter produces gas and oils that are less dense than water.
Finally, we returned to the estuary. It’s much larger than the first one we saw, and it’s flat, swampy with lots of distributaries, and chock full of the sediment and debris of the watershed above it.
View of the lake from the estuary. The red iron floc in the stream made for a beautiful contrast with the black of the decaying leaves. There is so much red precipitate that it is visible on the satellite image.
This less than three kilometer hike took the best part of two hours. But that’s pretty fast if you value your dawdling.
Way back in Cycle 3, our class had our immersion to Nashville. We stayed in villas in Montgomery Bell State Park. Dr. mentioned in his post, “Limestone Trails at Montgomery Bell State Park”, that we went on a hike. It said that we followed a stream and then followed a ridge trail back to the villas, but it never said what happened in-between that. I’m gonna tell what really happened on that hiking day at Montgomery Bell State Park.
Our class did follow a stream; we did get soaked with nasty water; we were trying to learn something about the boring rocks that I don’t remember; and were trying to see who would fall in the stream the most.
Fellow classmates climbing over big, boring, rocks!
After a long time of following the creek (mainly walking in it), we got near a children’s play-area. Dr. told us that we needed to get back, but that we weren’t tracing our steps back. We had to climb over more huge, boring rocks to get to the ridge trail. Dr. then told us to just follow the path. Seven of us went up ahead while the rest of the class stayed way behind.
Meanwhile, one student was assigned to be the last one of the group. He got ahead of Dr., by a couple of paces, but kept looking back to make sure Dr. was following us. One time he looked back, he realized that our teacher was gone! He told two other students what had happened, and they, freaking out, ran up trying to catch up to the rest of the group. They found us and filled us in.
We all thought we were going to die out there: we were gonna be eaten alive by mountain lions; we were gonna starve; we were gonna die of thirst because we were all too stupid to go back to the stream for water! We were all going to die no matter what, unless we found Dr. We didn’t know what to do.
Some of the so-called, “adventurous”, students ran back to find Dr., while one student continued to follow the trail. The rest of us just stayed put.
The group who ran back found Dr., dilly-dallying, while the group who stayed put tried to find the one student who’d ran up ahead of the main group. Soon enough, we were happy to see Dr. again (well some of us were), because we were tired of looking for where we had to go. The first thing I heard from him was, “You guys shouldn’t have wandered off.”
It wasn’t our fault that we didn’t know where Dr. was. He was busy taking pictures so the rest of us went up ahead. Because of this, we could have died. We didn’t know where to go. He should be in front, so we know where to go and so we don’t die. It was all of his fault not ours.
Hunting for microscopic fossils at the dinner table. Inside the circle is 100x magnification; outside the circle the magnification is 1.
My students will tell you that I’m never happier than when I have my cup of tea. On the night after our visit to Coon Creek, I put a tiny sample, about the size of a matchstick’s head, of sediment matrix on a microscope slide, and added a drop of water to disperse the grains. Then I sat there, while the chaos of dinner-making swirled around me, and searched for tiny, microscopic fossils of creatures that died long ago. With my cup of hot tea beside me, it was like sitting in the eye of a storm, flaming hamburgers be damned, a modicum of sanity in the asylum.
Quartz grains from Coon Creek Formation sediment seen under the microscope at 100x magnification. Quartz is easy to identify because of the way it breaks with curved fractures.
The first thing I noticed though were the quartz grains. They’re very small, silt-sized, but are the largest grains in the sediment. They’re pretty easy to identify because they break like glass, with curved, conchoidal fractures. They’re also pretty little things under the microscope; little, sharp-peaked, transparent mountains.
Other minerals are visible in the sediments. Though they're relatively large they're still dwarfed by the quartz (100x magnification).
Other minerals are visible in the slides, but they’re dwarfed in size and quantity by the quartz. Yet there is enough of the dark green, glauconite clay to bind the quartz grains together and protect the shells embedded in the sediment from dissolution by the universal solvent, water.
It’s interesting to observe these other minerals, because they take the more classic crystalline shapes and forms. The sharp edges are parallel to one another because of the alignment of the atoms in the mineral crystal.
Snail like shape of what's probably a planktonic (lives in the water) foram. (100x magnification).
Finding the micro-fossils took a little patience. The entire slide had only four obvious specimens. Since they’re so small that meant a lot of going back and forth under the small field of view of the 100 magnification objective lens. They look like foraminfera to me, but it’s been a while since I’ve encountered them. Foraminfera, or forams for short, are tiny organisms that secrete beautiful calcium carbonate shells. They can be found in, or in the sediments beneath, most of the world’s oceans, particularly in the warmer areas.
Finding forams in the Coon Creek Matrix is a nice little exercise. One of my students, seeing what I was doing, wanted to try it too, so she made her own slide and searched until she found her own specimen. It was somewhat inspiring, so I’ve put together a more detailed post about finding microfossils.
We also found a neat little shell that looks like the overlapping scales on a pine cone. We were disconnected from the internet, so I was only able to look it up when I got back to school.
What looks like a type of bolivina foraminfera. It's benthic, which means that it lives in the sediments not in the water. (100x magnification).
Dr. J Bret Bennington at Hofstra has posted a nice PowerPoint of his introduction to marine microfossils lecture. As a basic introduction, it’s quite comprehensible to middle-school students, or people like myself who did not pay as much attention as they should have during that part of Paleontology. Anyway, based on these notes, the pine-cone-shaped thing is probably a variety of bolivina, a benthic foraminfera. The Foraminifera.eu-Project, is a wonderful, volunteer-produced resource for pictures and identifying forams.
Bolivina are benthic, which means they spend most, if not all of their time in the mud. Planktonic micro-organisms, on the other hand, spend their lives floating around in the water.
Foraminfera have calcium carbonate shells, as do clams and oysters. In the shallow oceans there is a slow rain of them that cover the sea-bed over the millenia. You can end up with thick layers. In fact, the white cliffs of Dover are white because of all the microscopic calcium carbonate shells. In the deeper reaches of the oceans there are much fewer of these shells because they dissolve under high pressure. As a result, down there you tend to find microfossils of diatoms and radiolarians, things with silica shells. Silica is that same material from which glass is made, and is the same material in quartz.
Finding microfossils has actually been quite important for understanding the history of the Earth’s oceans and climate. But that’s another story.
On our immersion trip to the Nashville area we visited Abintra Montessori’s Middle School class. They’re an excellent school, about the same size we are with about a dozen students. Yet every time I visit another Montessori school I’m amazed by the subtle differences and remarkable similarities: they read many of the same books; they cover the same topics in social and natural science (as should be expected since we’re in the same state and are at the same academic level); but, most curiously, their students mirror my own pupils in independence, confidence and sociability.
I find this last congruence most interesting, because I’ve seen it in other places, too. It reflects a shared culture. One developed despite the fact that neither these students (mostly) nor their teachers had never met or even corresponded before.
There is a theory that Scandinavian countries can be more socialist because they are so culturally uniform and it is easier to connect with, and be emphatic to their fellow citizens. There is probably something similar in the Montessori secondary level in particular. Students are expected to display a large amount of independence in how they work and use their time. It’s why Montessori Middle Schools tend to be cautious about taking in students who do not have some Montessori background. It can often take a lot of time for students more familiar with the rigors of more traditional, command-and-control classrooms, to adapt to, and work effectively in, an environment with so much freedom and dependence on individual responsibility.
The differences between our schools are important, too. I’ve been thinking about Frederic Hess’ argument for more educational diversity in the U.S.. Teachers are different, parents’ philosophies of education are different, and students are different, so we should not expect a one-size-fits-all system of education to be the most effective.
Abintra and Lamplighter share the same philosophy, have students with a shared culture of independence and intellectual freedom, and basically the same curriculum. Yet as small, independent schools the teachers have a lot of freedom to adapt and interpret that curriculum based on their own expertise.
It also means that we have a lot to learn from each other.
