Steve Mirsky:    Welcome to Science Talk, the podcast of Scientific American, posted on August 15, 2016. I'm Steve Mirsky. On this episode, me. And I'm joined by the lovely and talented Robin Lloyd.

Robin Lloyd:      Hi, Steve.

Mirsky:               Hi, Robin. Robin Lloyd is a contributing editor at Scientific American, and the former -

Lloyd:                 - News editor.

Mirsky:               And she's also my wife.

Lloyd:                 It's true.

Mirsky:               And the reason that we are talking to you is because we recently did a trip through the Grand Canyon on the Colorado River that had a lot of sciency aspects to it, so we thought we would talk to you a little bit about that, and then also play some audio that I recorded in the Grand Canyon with some of the scientists who are on board the trip with us. And the Grand Canyon, if you've never been there, well go immediately, and go either – see it from the rims and get down into it if you can. It is truly astounding.

Lloyd:                 Yeah, it was spectacular, and I'd been there before, but I don't think I appreciated it quite as much when I was there in 1985 as I did on this trip.

Mirsky:               And I had been there about five years ago. Uh, we had a conference in Flagstaff, and we went over to the south rim, and I looked down, and you really are speechless. It's the first time I'd seen it in person, I'd seen it on television, seen pictures. But when you actually see the Grand Canyon in person, it's just beyond description.

Lloyd:                 It's difficult to perceive the distances and to anticipate how large they'll be, the magnitude, the scale of time and space that you're going to be taking in.

Mirsky:               This was a problem I'm sure I was having as we rafted through the Canyon. I'm sure I was not able to accurately gauge distances and heights because the scale is beyond anything that you're used to. And things that might have looked like they were – I don't know, maybe you'd guess they were 1,000 feet high, they might have been 2,000 feet high for all I know. Things you thought were a mile away, maybe they were five miles away. Just I was convinced that I was losing my ability to gauge these things, and the thing that really convinced me was on the second day as we were rafting and we got to Red Wall Cavern.

Lloyd:                 Right.

Mirsky:               Red Wall Cavern as you're going south along the river is on the left side, and it's – it looks like a significant canyon, cavern I should say. It looks like a low kind of gap between the bottom of the rock face and then a beach you can pull up to on a boat. Then I realized that these little dots I was seeing along the shoreline were human beings from other rafting trips who were visiting the cavern at the same time, and they just look so miniscule. You realize the unbelievably mammoth scale of this cavern, and that made me think about just how big and far away and huge and beyond your normal experience everything else there was.

                           The Red Wall Cavern had been described by John Wesley Powell who was the first guy, the first white guy that we know of anyway to go all the way down the river. He described it as this space that could hold 100,000 people, and it sounded ridiculous to people that read that description at the time, and it might not be able – I mean if you squeeze all those people in, maybe you could get 100,000 people in there, but once you get into that cavern, it's clear you could get 10,000 people in there without any trouble at all, maybe a few times that many. It's just that – that was really impressive to me just again in terms of the scales that you're looking at.

                           But we – let's backup and we talk about we put in at Lee's Ferry, which is where all the trips begin. And some people are brave enough to kayak down the Colorado, and some people are in smaller rafts, and some people are in these little boats called dories that are very famous for running that river. But we were on what's called a bologna boat.

Lloyd:                 It's a motorized raft.

Mirsky:               Of about 35 feet long. And it's got huge pontoons on both sides, inflatable pontoons, and those would be the bolognas, and it's virtually impossible to tip this thing over. The rapids will tip over a kayak easily I would think if you're an inexperienced kayaker, and the smaller rafts could go. But to tip over one of these bologna boats, you'd really have to go out of your way to try to tip it over I think. And there were 17 people I think in our party altogether plus five crew.

Lloyd:                 It was actually 20 people altogether in our group plus five crew members.

Mirsky:               Twenty people and the five crew, and that would – that is split over two boats, and the two boats would travel fairly close to each other. We were in the lead boat most days. You meandered down the river, and then you get to some rapids, and you shoot down the river, and the rapids in the Colorado River are scaled differently from there. They're rated differently. Most white water rapids are on a six point scale or a classification system where it's 1 through 6 and 6 being the worst, 5 being really, really bad, 6 being you could die on this one. But the Colorado has its own system from 1 to 10, 10 being the worst.

Lloyd:                 Well the most energetic and exciting.

Mirsky:               The most energetic and exciting, that's right.

Lloyd:                 The best to some.

Mirsky:               The best, and actually, after a while, it's so hot that you're rooting for some significant rapids because you know you'll get wet, and that'll cool you down again. But the rapids classification is interesting because each rapid gets a classification based on also the water flow at any time because the flow of the Colorado River is determined by the water that's released from the Glen Canyon Dam which is a few miles upstream from where we put in at Lee's Ferry.

                           So might be a little counterintuitive, but the lower the water flow, the worse the rapid can be. Because at a high water flow, you pretty much wash out the rapid. At a low water flow, the rocks and whatever other things in that spot in the water that can affect the turbulence, those get accentuated. So at low water flow, that's when the rapid can be really at its most violent. For many of them. For a few, it's the opposite, but for many of them. I mean some of them were – you got buffeted around pretty good if you didn't hold on while you were the raft, you would have been tossed off.

                           But the raft itself was – based on our observations of the second raft coming through after we'd come through the significant rapids and then turned around and watched the second boat coming through, we could see that even though it was getting pitched around quite a lot, it was nowhere near in danger of being turned on its side or anybody being tossed off unless they weren't holding on.

                           If you weren't holding on, there were lashes, lashing straps everywhere that you grabbed onto, and the boatmen would say for the really tough rapids, first of all, everybody had to get down onto the deck and hold on with both hands to the lashing straps. And if you did that, and you really did have to hold on, but if you did that, you were obviously going to be perfectly safe and not get tossed over. But if you weren't holding on, you could get pitched a fair distance I would think.

Lloyd:                 Sure. And of course, we were wearing life jackets, so if we had fallen in, eventually we would have popped up to the surface and presumably been fine.

Mirsky:               Eventually. Depends on how long you're – there's a situation where I think they call it you get washing machined where you can be caught in a – it's almost like a whirlpool that's been rotated 90 degrees, so you can get caught in a rapid, and you'll pop up, but you'll get plunged down again, and unless you can swim out of that while you're under water and pop up somewhere outside of that particular feature, you can do that a few times. And if you do that long enough, you might start breathing water. Without gills, that's a bad situation.

                           So anyway, we headed down the canyon, and I should say that the reason we did this particular trip was because it was put together by the National Center for Science Education, which is the Oakland based group that really does the frontline work with protecting evolution education in the nation's public schools. So the National Center for Science Education a while back realized that there were raft trips through the Grand Canyon that were put together by creationist groups who go through the canyon and interpret the geology they're observing from a young earth creationist perspective whereby the earth is approximately 6,000 years old, Noah's flood occurred approximately 4,400 years ago, and what you're seeing in the Grand Canyon according to the groups that do the raft trips from a creationist perspective, what they tell their patrons on these raft trips is what you're seeing is the result of Noah's flood.

                           So the National Center for Science Education decided to put together a raft trip, there's only one each summer, which for a little bit, they'll discuss what the creationists see, how they interpret what they're seeing, and then there's a geologist on board, fellow by the name of Steve Newton, and there's an evolutionary biologist who makes the trip, Josh Rozanow, and they will talk about various things that we're looking at from the scientific perspective. And so every once in a while we would pull over. Sometimes we'd get some short lectures, a minute or two while actually sitting on the boats.

                           But every once in a while, we'll pull over and get longer explanations from the scientists onboard, and we also had other scientists among the patrons who were making the trip. So a lot of people knew a lot of things and were able to share it, and that's what we spent a week doing. And but living on the Grand Canyon is – for a full week – eight days and seven nights was a pretty fascinating experience.

Lloyd:                 Yeah, the outfitters for our trip, Arizona Rafting Adventures provided sleeping bags, sleeping pads, dry bags for us to put gear in, and all our meals were prepared for us. It was wonderful. But we are – we helped in various capacities. We unloaded the boat every night and reloaded it again every morning. We made our own little campsites while the boat crew was preparing dinner.

Mirsky:               The crew would take out a four burner stove every night and set it up, and cook these unbelievable meals, and then make a hot breakfast as well. Then in the middle of the day, we would pull over, and they wouldn't unload the entire kitchen from the boats. They would just take out a table, and they had cold cuts and – and tortillas and bread, and we would usually have sandwiches for lunch. And of course, what everybody always wants to know is the bathroom facilities. So urine goes right in the river, and for the men, that was easy. For the women, slightly more of a challenge.

Lloyd:                 Right, and the idea there is that urine on land can disturb some of the plant life and other life there, where as if urine is put in the river, it's diluted to an extreme amount, and it's not going to pose as much or hardly any at all, or imperceptible or negligible impact of the life there, the ecosystem.

Mirsky:               One of the amazing things about the Colorado River, and which makes it eligible for urinating into directly, is just how much volume of water, how big the volume of water is that passes through the river constantly. So we were told that a good book to read before the trip was The Emerald Mile by Kevin Fedarko. And it's about a trip through the Colorado when these three fellows attempted to do a speed run where they try to get through the Colorado as fast as possible.

                           We took eight days. They did it in – well I don't want to spoil it for you. If you're interested in reading the book, which I highly recommend, shut your ears for a second, but they did it in about a day and a half because of certain conditions that existed when they put in. Okay, so welcome back everybody who didn't want that spoiler. So in addition to discussing the speed run, he has a lot of good material on the history of exploration of the river and the hydrodynamics of the river. The water is really a muddy brown because of how much silt it carries. And also the Colorado is dropping a couple thousand feet over the 224 miles that we traversed on the raft trip.

                           So it's falling like eight feet per mile on average. Most of that is in the rapids, but it's really a very steep river, and the water is really plowing through it. Fedarko writes this unusual combination of gradient volatility and sediment distinguishes the Colorado as the most impetuous river on the continent. And because of these qualities, no river on earth has ever cut canyons to rival those of the Colorado. So that's who you have to thank for the Grand Canyon is that Colorado River. So that's where we spent the week, sleeping on the banks of the river.

Lloyd:                 And the climate is worth mentioning. We were there in July. The temperatures – we didn't have equipment with us, but I suspect it was in the '90s, maybe 100s. Do you know, Steve?

Mirsky:               Well before we left when we had our orientation session in Flagstaff, they had a forecast that said – we left on a Friday, and they said that on that Friday, the orientation session was a Thursday night. They said Friday, the air temperature was going to be in the '90s, and all the subsequent days, the forecast was for air temperatures between 100 and 105.

Lloyd:                 Right. But so it's a dry heat, which is appreciated. Nonetheless, you feel quite hot when the sun is out and you're not in the shade. But the river temperature, the water temperature is in the low 50s. Right?

Mirsky:               It averages between 48 and 52 degrees.

Lloyd:        Right, so the river is always there to cool off.

Mirsky:               Which led to the expression that the boat people, our guides, shared with us.

Lloyd:                 If you're hot, you're stupid because you haven't jumped in the river or you haven't dunked a sarangue, these long scarves that a lot of us were advised to bring onto the trip into the river and then wrapped it over your head or around your shoulders and provided fantastic evaporative cooling.

Mirsky:               I spent the entire week – it may sound, again, counterintuitive, but I wore long pants and long-sleeve shirt and a big floppy hat all week in part to avoid sunburn, and I did sunburn the backs of my hands, which I did not have covered for the first three days. By Day 4, my hands were in pretty bad shape. My fingers were splitting at the – near my nails, and I was sunburned on the backs of my hands, but I took care of that with sunscreen and lotion and cotton gloves. Within a few days, my hands were fine again. But with the long sleeves and long pants and socks under my river sandals and the big floppy hat and the sarangue and life vest, you just keep them wet. You jump off, dunk yourself, get yourself completely soaked, get back on the boat.

                           If you pick your sarangue up and it's wet and you put it behind your head and you have any kind of a breeze, even a hot air breeze, you're really comfortable. It felt like you were in an air conditioned little space, and it was really quite comfortable. I've been adopting that philosophy since returning home by just keeping wet. Just throwing a hose over myself in the driveway on these – we've had a hot spell real recently and just employ that evaporative cooling. Oh yeah, we mentioned the urine situation, why it's okay to urinate directly in the river with this massive flow, but we didn't talk about solid waste, and this is an important subject.

                           The boat people, every night, would set up two facilities on usually opposite sides of the camp we would all be making, and they would be secluded enough so you'd have privacy, but they were outdoors. Beautiful views, and these are called groovers.

Lloyd:                 Yes, these are basically boxes with toilet seats fitted on top of them, so it kind of is like a toilet.

Mirsky:               Metal boxes.

Lloyd:                 Metal boxes, but the originator of the groover is the US military, and there wasn't a toilet seat on top of the box we have read. And so when you sat there to do your business, you get a little bit of a groove in your backside.

Mirsky:               On both – one on each cheek, apparently, as you're on the sides. And so that's why these things have traditionally been called groovers. And that solid waste got carted all week and back to a disposal facility when the thing was over, and we were all each given a groovette to keep by our campsite.

Lloyd:                 Actually, a small plastic painter's pale was what it was, and that helped you in the middle of the night if you were merely in need of urinating.

Mirsky:               Yeah because you really – we were all told to get headlamps for negotiating the campsites in the dark, but you know, you might have camped 50 yards from the river, and making that trip in the dark. There's driftwood lying around, rocks.

Lloyd:                 And there's night critters.

Mirsky:               And there's night critters, yes.

Lloyd:                 Could be scorpions, snakes, rodents. Perhaps bats. I mean none of them were really a big problem, but one could encounter them.

Mirsky:               Right, so you know, just peed in the bucket near your own little campsite, and then in the morning, you'd take it down to the river and dump it in. And then it would be gone, and you could then bathe right there if you wanted to just a few minutes later. You could bathe there, you could wash your clothes. I kept imagining my great grandmother seeing me doing these things and saying, "You're bathing in river? You bathe in river? You wash clothes in river? We escape Russia so you not have to do these things. What has happened to my family?"  And what else was she mad at? Oh yeah, she saw me unloading the boat at night and then loading it again in the morning. We would form long lines, and some of these bags were really pretty heavy, but we'd all pass the bag down to the next person in the line and get it on the boat.

                           And I imagine my grandmother saying, "You got job? You got job as longshoreman. That's good job. What they pay you? Nothing? You pay them to go on this trip and carry – my family, I'm so ashamed."  So that's what I was thinking. So now you know what it was like. We almost pitched the tent on the first night. The tents were supplied by the rafting company because it had rained a little bit on the first day, and we decided that on the first night not to pitch the tent, even though there was a slight threat of rain that first night because number one, we were lazy. But number two, we thought it would be really cool to be outside. Also, it was still pretty hot at night, and to be outside was – without – you know, to be out in the open without the tent was better because you got at least a little bit of a breeze over you and you could see the stars, which were spectacular.

Lloyd:                 Spectacular. You could see the Milky Way easily every night, just watching them come out between 9:00 and 11:00 every night was a thrill.

Mirsky:               Yeah. Among the bats, which were flying around every night.

Lloyd:                 Yes, at dusk.

Mirsky:               And getting really quite close to your face. So we didn't pitch the tent and we got away with it because it didn't rain that first night. And then there was no threat of rain whatsoever the whole rest of the trip. So we never put a tent up. We slept out in the open every night, and it was – it was great. You wake up at 3:00 in the morning and great entertainment, just looking at the stars up there. Now I'm afraid of heights, and I'm also afraid of turbulent water, so this was perfect trip for me to go on. But I really wanted to go because it was National Center for Science Education, and I wanted to hear the lectures, and I wanted to see the Grand Canyon from the bottom.

                           And there were some of those rapids have terrific names.

Lloyd:                 The fourth-day rapids included Hance, which is a class 9 Sock Dolliger, Grapevine, Zoroaster, Granite. These are all pretty significant rapids. But the biggie was Crystal.

Mirsky:               Yeah, Crystal Rapid has a great story behind it. But first, I want to talk about some of the names. Like Sock Dolliger apparently means a knockout punch.

Lloyd:                 Right, that was the term at the time that it was named for a knockout punch.

Mirsky:               And then there was hermit – Hermit Rapid was named after a hermit who lived out there, and Boucher Rapid, which is the next rapid down from Hermit Rapid, is named after Bouchet who was the hermit. So both of those rapids are named after the same guy. So but Crystal Rapid, Fedarko in The Emerald Mile goes into its formation in some detail because Crystal Rapid as it exists today is only dates back to 1966. In December of 1966, there was this three-day rain, and massive amounts of the rock face right at this part of the river came falling off the canyon walls and created the Crystal Rapid that currently exists, which at first some people worried might not even be possible. As our boatman was explaining as we approached it, he called it – he said this event, this rainfall event in 1966 had formed, "The ulcer-inducing spectacle," known as Crystal Rapid.

Robin Lloyd:      And our boat crew had no trouble at all navigating it. We were inundated a couple times by some pretty nice waves of cool water.

Mirsky:               Exactly. And one of the other interesting things about the formation of Crystal Rapid was it happened in December of 1966, and nobody even knew that this event had happened. You know, millions of tons of rock falling down. Nobody knew about it until a while later when a helicopter -

Lloyd:                 - February or March, I believe.

Mirsky:               Yeah, a helicopter pilot was making a trip down the canyon and noticed that this feature was new. You know, he knew the canyon well and said, "That's different," and alerted the authorities. All the boat crews had to study it and learn how to go through it. They had to come up with new techniques to traverse Crystal Rapid. The worst rapid we did though, I don't know if it was the worse one we actually went through, but the one with the worst reputation -

Lloyd:                 The highest rated -

Mirsky:               Yeah, was Lava Falls on the seventh day.

Lloyd:                 And that's the one rapid that our crew actually pulled over before we went through and scouted. All the others, they were prepared already, they knew what to expect, but lava, there's great respect for lava, and I think most boat crews do this before they run lava.

Mirsky:               Yeah, because all these rapids, they have certain general features that are consistent, but they're different every single day. But everybody made it through okay. Nobody was thrown off either of the boats the entire trip, which was – so we had that going for us. We also would stop during the day as we were going through the river and do hikes up side canyons.

Lloyd:                 Yeah, a lot of us felt that some of the greatest moments of the trip, the most spectacular things we saw, we encountered on the side canyon hikes. Waterfalls, crevices that we inched through, steep cliff faces that we pulled ourselves up. A lot of us were pretty challenged with the bouldering and rock climbing that we did some ledges we crept around, but the guys were very encouraging and spotted us and told us where to put our left foot and right foot and left hand and right hand when we got stuck. A lot of us at the end were rewarded by these waterfalls, the blue, blue rivers. The side canyon – the rivers that carve some of these side canyons are beautiful little rivers, including the little Colorado, which is an aquamarine that you've never seen before. That side of canyon hike was really fun. And at one point, we stop and settle down on some ledges, and we were taught how to turn our life jackets around and ride the river down.

                           It had a little descent, and we rode it down like a flume at a water park, only this was a natural flume that we got to ride down. It was really fun.

Mirsky:               Yeah, you take the life jacket off, and you wear it like a diaper, basically. The little Colorado, where it joined the main Colorado, which we're going down, practically a straight line where the muddy brown water of the Colorado meets the clear aquamarine beautiful water of the little Colorado. And there are these brilliant green rushes that are growing right along the sides of the little Colorado at that point. So you have this amazing contrast with the blue water, the green rushes, this line of demarcation, and then chocolate pudding, and that was a memorable sight.

Lloyd:                 Yeah, this is called the confluence of these two rivers. And there's actually a proposal for development at the top of the canyon above the little Colorado. A gondola would carry tourists down to the confluence of some concern to people in the area and to anyone who loves the Grand Canyon. That is still being considered. It's not decided yet whether this development will go through.

Mirsky:               So you prepare for a trip like this that was checklists of items that you had to bring, like the headlamp, and the sarangue was highly recommended. But you can never be completely prepared until you're at a place that's going to pose particular challenges. And what I learned was that a touch screen Kindle is not going to work. It's a touch screen, so it's not illuminated. It's not backlit, so I would try to read – this whole experiment lasted about two minutes on night number one. I would try to read with the headlamp, so I put the headlamp on. And looking at the Kindle screen.

                           There were no mosquitoes, but there were plenty of insects, and the insects were attracted to the headlamp light, and they landed on the touch screen or the Kindle, and they started turning the page.

Lloyd:                 Closed the circuit.

Mirsky:               They turned the page, changed the type size, a fly or I think it was a fly landed and started walking around, and the Kindle just went berserk. So I had no choice but to turn the light off, shut the Kindle. I could still read it during the day. We would make camp by usually about 4:00 in the afternoon, so I had a few hours of downtime where I could read if I felt like it. But at night, no. I filed the Kindle away. Fortunately, there was a great planetarium show every night, so I didn't have to rely on the touch screen Kindle for entertainment.

                           So we have recordings I made of the geologist Steve Newton and the evolutionary biologist Josh Rozanow at a couple of sites along the canyon, and I'm going to put those out in our next episode.