Investigate mysterious features with a geologist

sometimes while exploring our wonderful world we encounter amazing features that seemingly have no explanation these situations can be challenging for a geologist but also bring great enjoyment what a beautiful day out here in the desert of Utah I'm about 20 miles south of a community named Green River and I'm out here to explore some fascinating features that my son-in-law Jason told me about he knows this whole country really well and he came across some of these features and he didn't know what to think of them and I found them quite interesting and so I think you will too and we're going to use the scientific method to try to understand just what how these features were created and what was involved I'm looking forward to this and let's get going well it's been a beautiful hike a bit longer than I thought it might be and I've come up over the hill and here I think I see something over here let's go take a look should we boy this is looking interesting to me uh hmm is it circular not sure yet I get the sense it is beautiful hiking out here what a beautiful day wow this looks pretty tall taller than me yeah huh it is circular definitely wow I can see already this is going to take some serious detective work you know geology you get out and you hike around you never know what you stumble on earlier I stunned stumbled on some just amazing agates out here love the coloring in them coming out of the Morrison formation but this this is pretty well intriguing what could what could this be I'll tell you what it reminds me of it reminds me of tower ruins they're quite common out in the desert in Utah where the natives built these tower-like ruins that had sometimes multiple floors this is a little different the blocks look quite a bit bigger than the ones I've seen elsewhere but it's sure neat it kind of gives me a feeling that's a little older looks like it's kind of falling apart in front here but uh let's take a little closer look at some of the features in here okay as I come up to this wall oh it's so beautiful and I feel it it feels well yeah feels like Sandstone now that's not surprising is it natives would be using sandstone and creating their their structures it is a sandstone and it's composed primarily of quartz and then darker colored lithic fragments or rock fragments large blocks that are circular shaped these big Stones they almost look like they've been specially shaped just to fit around the these uh the corners hmm around the circle so to speak one other thing I'll point out is I see some pretty interesting patterns in this Stone like this see these lines in here those are interesting to me oh here's a piece that's fallen off right here right there very interesting lines all throughout the stone kind of an anastomosing pattern is what I call that Network you know that network of veins or something in there you know I don't want to jump to any conclusions yet when you first come up on something like this you want to take your time you want to look at it for a while and you want to hike around and see what else you might see you never know you know I've noticed something about these anastomosing patterns if we look at this rock here that's tumbled off we see the patterns in there and then we come into some rocks that are in place see this lighter color sheet in here I think that's one of those veins that are in there really fascinating you can see the surface here right down through here yeah hmm so they seem to go down through the Rock you wonder what was going on don't you let's just keep looking for Clues and here's another block that has these beautiful patterns in I don't want to get too focused on these but aren't they neat I think they're beautiful that's one reason I'm focusing on them so uh wow so we've got a few pieces of the puzzle to consider so I've made a few early observations and I know there's going to be quite a few more and and I certainly don't want to jump to any kind of conclusions until I get a chance to look around I think I'm going to be hiking a few miles and this could take a couple days so we'll continue now in the spirit of good science I've taken some time a couple hours two or three hours actually I've really enjoyed this area and hiked around just looking around for some features and it turns out there are other very interesting features close by to here so let's take a look at those and see if it adds to the story just a short walk away is another interesting feature so here we have a another rounded nice circular wall that goes clear around and it's over twice as big as the first feature and it's more heavily eroded it looks older or it's been more heavily eroded for sure I did observe the anastomosing patterns here too let's go take a look at what I call feature number three with another short hike we come to the third feature and to feature three it's kind of hard to see from just a low camera angle like this but from the Drone of course what we saw was quite nice the interesting thing about this two things I'll point out one is it's it's the biggest one of all it's 75 feet or so in diameter huh and the wall is thinner I'm saying the wall here is typically only a foot or so thick so that's interesting to me but I'll tell you something that really made me think I had the Good Fortune of doing my Master's field work on field geology on the Moen copy formation near the Grand Canyon and as part of that I got to do a lot of the ground geology at wapaki National Monument where they have many ruins and one thing they have there that's really cool is a big circular ball cord where they played ball they had games that they played within that Court and I'll tell you this kind of reminds me of a big ball cord or something uh yeah it's just fun to think about and I'm also thinking about the geology and what could possibly be creating features like this geologically that's a puzzle too I can tell you no matter where we're going here it's very exciting and it's very unusual I believe so another feature I want to show you is kind of a miniature version of everything we've been seeing bigger things what about this guy he's only like three feet in diameter really interesting he's got a there's a kind of a hole in the middle of it in fact there's really good evidence for it as you come around the corner this piece of rock here used to sit right on top and you can see a well-formed well half circle so we have another observation now we have miniature versions and this one's beautiful the next day I met with a couple friends to go on a hike and we encountered these two small versions as well it looks like they're just coming right out of the sandstone well we're going to keep on investigating and let's see where it takes us [Music] the scientific method tells us that we should make an observation as something anomalous that we've done and then you explore the broader region you look for context and you try to find other features that might help you understand what might be going on and so you might think well I think I might have some ideas and then you find this well isn't this an amazing feature wow you know I love when you get out and hike around and see this great Earth and all the Creations around you when you bump into things that just really impress you geologically and aesthetically as well but to the observations of this this really interesting feature first of all it's quite different from what we've seen really hmm the only thing that's the same is that it's circular okay and it has weathered out in relief we've seen some that have weathered out in relief some of them not so much furthermore this feature has a cylindrical shape that is filled with fine-grained sandstone and siltstone and seems to be coming out from under the ground now a couple other key observations I want to make here is that I see like a wrap is sheath a wrapping of red silt Stone around this the core of this feature is a light colored sandstone and the outer edge is the typical darker red Sandstone that we see in the area in the front part here the outer sheath of this red Sandstone has been eroded away let's take a closer look at the contact between these two sandstones let's zoom in and look here isn't this a fascinating contact it's quite Sharp here's another view of it in a different area another observation is this is so different from all the rock around here instead of nice layers that we see in the in the stratigraphy or the layering of the rock out here we see this Blobby look big boulders that are irregular shaped and weathered out kind of smooth fascinating isn't it and if this is geologic then I better have a good hypothesis or a good set of observations that that tell us how this could happen let's continue looking around and making observations of other features that have similarities to this and hopefully with all these observations put together we have our aha moment here is a similar large feature about a half mile away aren't these white lines that we see scattered across the Sandstone interesting it turns out these are fractures and as you look at them you can see that the color has been removed from the Sandstone along the fractures and it reminds me of what we've seen in the core of some of these features where the color has been removed now this is interesting here we see a very circular feature that has negative relief it's it's a slight depression and furthermore it has a darker red Sandstone within it looking from a much higher Google Earth view we see the two features that we have just reviewed and now we have a total of four large positive relief features and if you look closely there's several negative relief or slightly positive relief features in this area here is a large feature being eroded out of the hillside I was able to examine several like this many of the features have several concentric circles within it as this feature shows well here I am for scale I found several samples of the fascinating anastomizing fracture pattern in this one in this region we see many modestly sized positive relief features these four features are some 50 miles to the south of the main study area have fun counting up how many features you can see in this View well it's getting late in the day the wind has really come up this is day two of exploring these features I've had to go to my windy Wyoming hat because of this but I wanted to summarize some of the things that we've observed about these features number one is the shape now when we look down they tend to be circular sometimes very circular when we look down from above on them they also are cylindrical they're tube shaped okay another thing we've observed is the bleaching of The Rock and we see that in parts of these features and some little sections of them we've seen it along fractures in the area some of these fractures heading right to these these features and others in the general area and so that's giving us a clue that fluids have moved along fractures near to these and within them to to bleach out this hematite staining and speaking of fractures remember this beautiful anastomosing network of fractures that we've seen and you wonder how does that happen wow this wind uh well I've seen that happen where volcanic material is injected into rock and it just fractures up and injects and makes these nice anastomosing fracture patterns that's one time I've seen that pattern now let's think a brainstorm a minute this is where it's so fun to do geology is to brainstorm and think where do I see that if it's a geologic process and humans aren't involved how could this happen well what makes circular shapes and or cylindrical tubes hmm mud pots and Yellowstone you know I'm reminded of those every time I cook oatmeal I see bubbling bubbles come up through and they're circular shaped when looking down okay uh car sting or sinkholes we can have something underground that is dissolved and things start collapsing into it and filling in the hole with new material that's a possibility for sure one obvious one is that we know volcanoes when the magma from underneath comes from deep underground and up through the rock it often is circular looking from above and Tube shaped that plug right in the core of the volcano so it's it's fun to be thinking oh wow so we have a few options here don't we and how could this all tie together so these are things for us to consider and think about we're going to make some more observations and then we'll tie it all together into an unbelievable geologic story as I hike along I decide that although the first feature was reminiscent of a tower ruin it couldn't be man-made there are too many other very large features that have no resemblance to man-made structures in my mind I rule out mud pots these features are too large and are composed of sand I also easily roll out volcanic involvement I haven't seen any volcanic rocks that leaves me with the casting or the sinkhole hypothesis yet I haven't seen any collapsed pieces of rock that we call brecha within them and there are other issues I have with this hypothesis I'm thinking there's another better idea it's so fun to be out here in the wide open all on your own exploring the geology enjoying the beauty but one of the side benefits that you receive is sometimes you discover something that that really makes an impression on you and you have an aha moment oh I've got it now for some years I've had a problem that is I've been seeing some beautiful photographs with big holes and very resistant wind blown or aeolian sandstone and these big holes have cottonwood trees some of them they're so big and they're circular and photographers have have made beautiful photos of these scenes and I couldn't figure out what geologic process could do such a thing and so when I started this Venture of looking for at these positive relief features that we've been seeing I didn't know that it would realize that it would come to an answer or help me come to an answer about the big circular holes so here I am in an area where I have a nice hole in front of me it's not real deep this particular one and now I understand what happened the same process that created the positive features also in some circumstances created negative features and holds down into the ground that means this material that was in here was less resistant to erosion than this sturdy Sandstone I'm standing on and therefore it erodes more easily and creates a hole a beautiful circular hole boy this is fun so we have two large slightly positive features adjacent to well-defined holes that go into the Sandstone it seems to me that it's very likely that the same processes are responsible for both types of features here's another nice example of these holes in the Sandstone notice the cows for scale my observations here don't prove that the giant holes with trees in them some hundred miles away resulted from the same processes but it seems likely to me more work needs to be done well we've made our observations and it's time to get down to it and figure out what happened first thing let's talk about Karsten because that's been a key theory that we've used to think about I have a sketch here to show Karsten it's cross-sectional with the tree here to show that and down deep in blue here I've put some rock layers in that can be dissolved by water and this is typically Limestone or Dolomite or maybe an evaporite like anhydride and it can dissolve and form a big cavern and The Rock starts collapsing within so it forms the cavern and all these layers above start collapsing down in and it can work up through time it can just keep collapsing and propagate clear up to the surface I've seen them in seismic data propagate up from the original Cavern some thousand feet or so and one might imagine that well with ground Waters now you have all this collapsed material in here that it could cement up really tight very common process and make it very durable and resistant to erosion and then this rock around here can't really quickly and you have a a positive feature like we've observed um so it's a very viable Theory but I don't like it and why well all these collapse blocks are very angular and they can be very big and right down to the small but they're angular and they're obvious and I haven't seen any in any of these features these collapse blocks we've also seen very small features three feet in diameter if you have a hole in the ground that's just three feet in diameter down underneath somewhere or maybe a little bigger it's not going to collapse like a karst and finally The Rock that could potentially collapse is some four thousand feet deeper than the rock we've been observing The Rock we're observing have been observing is the Entrada formation Jurassic age and and this unit down here that could potentially curse like I'm talking about is some four thousand feet deeper so for all those Reasons I'm just not comfortable with the karstening theory and that puts me in a real pickle because now what uh I don't have any volcanic rock it reminds me some of volcanic features we see especially you know the fracturing and and this network this anastomosing network of veins that occurs in high pressure situations like I've mentioned in intrusive volcanics or in granites that intrude the country rock you'll see these patterns of forceful injection so with these observations really what you need is a volcano of sand and silt that seems rather impossible doesn't it well it turns out there is a possible way for that to occur I'm sure many of you have had the experience of walking down along a beach and having fun with your kids or grandkids or siblings or something and you get there just above the waterways and you start jumping around and everything starts getting kind of weird on you doesn't it you have water start coming up the you start sinking into the ground and that's called liquefaction and I've found a little place here along a creek near my house that I hope will demonstrate this principle for those of you that aren't familiar with it so I'm above the water I'd say oh a good foot and let me work out here it feels pretty firm right here and if I and and then if I start doing this just tap in my foot oh it's all ready this is happening pretty quickly here I probably could have gone higher up on the bank just tap it around a large area is starting to get uh kind of jiggly kind of like jello this is very fine grained here more of silt it's not a nice sand and demonstrate it better but you see I'm just going down down until I hit hard ground underneath here and if there were more sand under here I could keep keep going probably to my waist even old guys like me can have fun in the sand in the mud it's getting hard to move my feet around there's water coming out and running off down below this is kind of like quicksand ah and there I am Up On Solid Ground again so it turns out that this process that we call liquefaction is the key to all the features that we've been observing now there's more than just pure liquefaction involved we have to have some special conditions maybe you'll think of them if you think about it a minute but this is the fundamental principle at play boy this liquefaction is pretty interesting and we need to know a bit more about it so we can understand these these features in the end right I have three glasses that I've sketched here full of sand this first glass let's focus on it these larger circles in here sand grains so we're zoomed in this is just a schematic now let's put water in there and I'll just sketch a little blue in the in between the sand grains it completely fills with water I'm not going to do that that'd take forever okay all the way up so it's fully water saturated now this you can see is high porosity and in other words there's a lot of empty space in here 45 is typical if you just take sand and deposit it put it in a cup uh whatever and not compact at 40 45 of the space is empty and we filled it with water but if you look closely I've tried to sketch it here the sand grains are still all touching each other to support weight so when I walk out on this and stand on this my weight is being supported by the actual sand grains not the water the sand grains but if you shake it up like I did with my feed or Like An Earthquake could do well then the world changes and that's step two right here you see when you shake things they want to resettle down and compact more efficiently and better that's how it kind of works so you start to shake it and these Gran sand grains are no longer in contact with each other let me put some water in here in between all these uh sand grains all over in here with this blue water but the grains no longer are touching each other so that means it can't support weight it's more like a liquid it really is a liquid at this point and this is what causes all the problems in certain situations in earthquakes where buildings start to sink in or cars just sink in just wow kind of magical terrifying but interesting because it loses the strength and then to phase three and that's where all the sand grains have resettled they're more efficiently compacted now let's say instead of 45 porosity they have 40 percent porosity or instead of 40 they have 35 or something along like that you still have water between all the sand grains here but but you don't have near as much within the sand because it's compacted better so the water leaves and comes up and fills in so the total volume of sand and water is the same as over here it's just that a lot of the water now is just free floating right here on top of the sand wow and that's why an earthquake sometimes they'll see water on the surface as it just comes up out of nowhere all of a sudden you have like lights forming fascinating isn't it and you wonder to yourself well how does this create these features and that's a fair question because nothing I've shown you here really would create what we've been looking at you have to have this in combination with some special conditions and here are the special conditions cross-sectional view I've got my little tree here layered layered rock that are seals meaning fluid has a hard time pushing through it like shales and silt Stones sometimes too that interbedded here and we see that out where we're at above the sandstones that I was hiking around we would see these nice layered rocks like this and then you have the nice Sandstone High porosity it has not yet started to cement together which is so common in geology is the sand grains and any rocks and carbonates anything as it gets buried through time it starts to cement together through precipitation of cement in the water well this hasn't happened High porosity hasn't compacted not buried very deep deeply as near as I can tell my estimates are you know 100 feet or so 200 feet of burial depth not very deep water in between all these sand grains so it's fully saturated like we saw in the in the cup in the glass and the first example this is an unstable situation potentially if you shake the ground now when you shake the ground instead of all this weight of this rock being supported by sand grains as you'll recall now it's being supported by water essentially it's supported by liquid and this is a very unstable situation it turns out that the pressure the weight the pressure on this is a function of how thick this is of course how much weight you have and it's about one PSI per foot so let's say that's a hundred feet you've put a hundred PSI of pressure on here on this fluid that's like having a hose if you buried a hose down under here 100 feet and had it 100 100 PSI well that's way high pressure Rock through lots of studies we know can only handle about 0.7 PSI per foot so it can at 70 PSI it breaks that's a good rule of thumb so it just can't handle all this pressure sitting underneath of this fluid and it immediately violently and I mean immediately when you have an earthquake this this cannot support it this water has to escape it has to and immediately and violently so it breaks through just like a volcano breaks through to the surface right up fluids coming out water pouring out onto the surface like this and it's such a violent powerful movement that it brings sand to with it the sand and the silt in here it it brings it up as well all through here and creates a sand volcano well there you go and it has this pipe right here where it brings up all the sand so just how much water could this be well it's fairly easy to estimate I mean using some you have to make some assumptions but we know the Sandstone the Entrada sandstones 200 feet thick or so the Navajo Sandstone which does this as well is like 500 feet thick and imagine if you have 40 percent porosity in there and you reduce that to 35 percent porosity what that really means is for if you have for every hundred feet you would have five feet of water because of that if you re-assemble the sand grains and compact them more efficiently and this happens almost instantly so in the Entrada case and the Slick Rock Entrada case that's 200 feet that's like 10 feet of water immediately that's like almost like a lake coming here and it's got to get rid of it all that water these features as near as I could tell looking at some of the hillsides where we could see them in the hillsides pushed up through easily 100 to 150 feet of rock and think of all these features we've seen I'm quite confident that all of those occurred essentially at one time can you imagine walking around out there having an earthquake go off and have all these sand volcanoes some small some big just going off everywhere all around you it'd be uh rather alarming and now that you've had this violent pressure release at some point it kind of relaxes and you have this full of sand and now you have a conduit for fluids to flow through through time through geologic time and this can be cemented up we're always cementing Rock you're going to learn with me and become more durable than what's around it to make it really clear how we're left with these positive features and negative features let's erode this through time but before I do that we I showed you at least one example where we had most of the feature just still sitting in the hillside right up through clear to pretty much the top now erosion takes over and let's assume that this pipe is strong it's been cemented good so we start eroding things away through time I wrote this and we keep keep coming down but we get to this layer okay but we're left with this positive feature right here I'll put it in red here and it erodes down to there but it keeps going but this is always higher it stays higher because it just can't erode as quickly so we keep moving it down moving it down and finally let's say we get clear down here eroded off erode everything away this is several of them we saw this way many of them write down to there and so there you have it a positive relief circular or tubular shape feature poking above the ground and then of course we can have the opposite happen where this is weaker and it just maintains a hole in the ground of various depths well I can only hope you've enjoyed this as much as I've enjoyed making this video thank you for watching

Channel: Myron Cook

Views: 422,763

Keywords:

Id: 3JraT49a1tw

Length: 38min 42sec (2322 seconds)

Published: Thu May 25 2023