Arches, Hoodoos, and other strange rock formations

Before we went to Goblin Valley, we talked about some of the unique geologic features in Southern Utah. It's fascinating how the right conditions came together to produce these amazing formations! You can read more about how arches are formed here, about the Bryce Canyon hoodoos here and here, about the San Rafael Swell here, about slot canyons here, and about Goblin Valley here. And those are only a few of the interesting places nearby!

Then, we made a "sand clay" similar to this one (I didn't use alum in mine) and the children formed their own rock features. They loved doing this.

Erosion, Mountains, Rivers, Canyons

It's hard when posting about this subject, as it was when teaching it, to sort things into discrete subjects. Erosion and weathering are inextricably linked with canyon formation, and mountains and plate tectonics go together, but erosion goes with mountains too, and you can't separate rivers and water erosion. I'll do my best to place related topics in the same post, but if you need more ideas, you can check the tags at the bottom of the post too.

We did several small activities to demonstrate water erosion and weathering. We poured a small stream of water into a pan filled with sediment, then inclined the pan and watched how the water moved. We could see the gradual wearing of a channel, as well as the spreading out of the water into as it slowed or the slope decreased. We talked about deltas and alluvial fans (here is a page with related activities), as well as meanders and oxbow lakes.

Next we observed the effects of wave erosion on coastlines. We buried several cylinders of clay (representing layers of harder rock) in a pile of sand (the softer rock). Then we filled the rest of the pan with water and gently rocked the pan back and forth to make waves:

As you can see, the waves gradually picked up the sediment on the coastline and deposited it farther out, leaving a smoothed-out coastline and exposing the rock stacks. Some of the stacks were even left standing alone in the water. We've seen lots of examples of these types of stacks when we go to the beach (Haystack Rock in Oregon, for example). Some even form arches.

We watched the carving action of water as it runs down a channel. We formed several "canyons" in the yard, and saw that the river deposits sediments downstream in deltas as well. This is an even better way to observe meanders, as a slope evens out.

And of course we made play-doh mountains of various sorts: fold mountains, fault-block mountains, volcanic mountains, etc.

You can find several other erosion and weathering activities at the bottom of this post.

Here are some illustrations of anticlines and synclines.

You can also see examples of mountains in the Plate Tectonics post.

Here's a cute landforms flipbook to make.

Sediments and Erosion

Somehow in all my years of studying geology, I never understood that clay and silt and sand are simply names for materials composed of different sizes of sediment! We collected samples of each type and sorted them onto a plate, and then looked at them under the microscope.

Here's what sand looked like. Cool, huh? Like teeny pebbles. Which, of course, it is!

We also looked at how weathering and erosion affects different sediments. 

You can see, as we dropped water on our "mountain," the water wore away at the slopes, and formed river channels where it "preferred" to flow. You can also see the deposition of sediment at the bottom of the "mountain."

Wind plays a part in weathering and erosion as well.

Eventually, the mountain is all worn away and the sediment has been deposited throughout the flood plain.

We looked at different sizes of sediment too. The water, obviously, had less of an effect on large "boulders" than it did on smaller sediments.

After flooding the sediments, they mixed and settled. Then we allowed the water to evaporate for a few days, and when it was gone, we had a "sedimentary rock" composed of the old sediment.

We also repeated an activity we've done before, where you put different sizes of soil/sediment into a bottle, add water, and shake it up. The sediments mix and then settle to the bottom in layers sorted roughly by size. It's cool to see it work.

More sedimentary rock activities—here.

Dinosaur National Monument Field Trip

In all my years living in Utah, I've never been to Dinosaur National Monument before! We almost didn't go this time, because it's not really on the way to…anywhere, and Sam was going to be out of town on the only weekend we had free, so I wasn't sure I wanted to drive the six hours round trip by myself! But this is a place where Homeschooling has been so good for me. Normally, I very much like staying home where it's cozy. It takes a great act of will for me to decide to get us ALL out of the house. But for some reason, when I am thinking of myself as a teacher instead of a mom, my willingness level goes up. I think to myself, "This would be the greatest field trip to teach this concept…how can I deprive my students of that chance?" :) 

So, we packed up lots of celery and almonds and apple chips (to keep me awake…my jaw ached for the whole weekend afterwards, but at least I didn't fall asleep!) and a picnic for lunch, and headed off early in the morning toward Vernal.

The drive was extra beautiful. The mountains were at their greenest and everything was glowing in the sun. Don't worry, I had my trusty assistant Abe take these pictures while we drove.

At the quarry there's a huge wall of fossils they've preserved just as they were found in the ground. It's completely covered with bones! You can touch the actual dinosaur bones in the wall. That was really cool.

There's a cute little museum with allosaurus skeletons and such. I heard somewhere that there are so many allosaurus bones in Utah, paleontologists don't even bother to collect them anymore!

The tram ride from the visitor's center up to the quarry was a big hit—so much so that we rode it up and back three times. :)

It even coaxed a smile from Mr. Grump.

I liked the dinosaur bones, of course, but my favorite thing about Dinosaur National Monument was the scenery! I didn't know there was so much cool geologic stuff to see! You can read more about it here—this whole area was a huge bed of sediments nine miles (!!) deep. Then the uplift of the Rocky Mountains, and the downcutting of the Green River, exposed those layers until you can now see more than 20 geologic as you go down the river! It's pretty amazing (and of course we couldn't see everything from the little driving around we did—you'd have to float down the river). The layer the dinosaur bones are in, the Morrison Formation, is just one of the many layers, and a relatively young one at that. There are much older rocks exposed in other layers!

This book is another great one for talking about what geologic features you can see in Dinosaur National Monument, and along the way.

Cactus rose. I told you everything was green and blooming!

The weather was awesome. We could see a rainstorm blowing in over the east mountains while we ate our picnic. It started raining just as we finished and threw away our last garbage bag!

Goldie was very excited to run through the rain :)

There are some cool petroglyphs in the area, just a little way off the road.

I love these strange, colorful formations!

There's a Natural History Museum in Vernal that we stopped at too. It's a fun museum, with activity areas for the kids and a dinosaur sculpture garden outside. 

We all tried to get Goldie to stand by this mammoth, since she loves elephants, but he made her quite nervous.

We especially liked the variety of fossils, and the huge chart along one wall showing all the geologic layers and how they were. 

And the enormous diplodocus skeleton in the lobby, of course.

The whole area around Dinosaur National Monument is really beautiful. There were a few farms on top of a plateau that overlooked the park. I can't imagine what it would be like to step outside every day and see this view:

What an amazing place! I'm so glad we live (fairly) close by!