Seal Rock (San Mateo County, California)

Transcription

There's a place on the San Mateo County coast where you can see whales, sea birds, native plants, and eons of geologic history. Join me on the Devil's Slide Trail Experts will tell us why this is such a special place. Welcome to Devil's SlideTrail located just five miles south of San Francisco off Highway 1 and I'm here with Kathy Gesley Hello, Kathy. Tell us about the trail. The trail is a county trail. Its 1.3 miles Its a marked and paved so there are designated places for walking and biking the best way to bike is cut to go from the north to the south and are there are three platforms along the trail that allow you to rest and watch their arm birds look at the bird sanctuary and look at the beautiful ocean views it's a very intimate trail that really is in close so it's safe to bring children lot of our families are bringing their kids with the our stroller and kids walking along and they all do really well on the trail so Kathy what's the best way to get to double slide trail and where do you park the best way is to access it through public transportation SamTrans has a regular bus on a daily basis number seventeen and on the weekend there's a double slide our ride that comes from win a bar parking area up to the north end a parking is limited are both the north and the south end you can get to the south and through the tunnel the parking is arm difficult especially I'm busy times on their weekends after eleven o'clock for kathy was the best to get a good for walking on the trail the basic thing to remember is to stay within the trail boundaries arm their markings on the trail you wanna stay on the walk inside bikers stay on their bike inside and I if you have a dog please keep the dog on leash so that the dog is safe are for the other walkers so if you have a question just ask a double slide trail ambassador that sounds great let's go take a walk sounds good my getting around the coast has always been a challenge to rate your I the Indian tribes around here had to pick their way through these areas where we're standing right now and of course when are California became part of the United States there was a whole lot of the talk about developing the area more in 1865 was the first time the people started thinking about maybe we should build a railroad out here and then in 1881 are the ocean shore railroad was incorporated in Sacramento people and thought well railroads are springing up all over the west all over the United States why not build here it was a great idea to cut down transportation time between San Francisco and Santa Cruz unfortunately they chose 1905 as the year to do that and one year later the earthquake of 1906 really knocked out most of the equipment and most at the throughway that they had here at Devil's slide they were able to I keep things going through 1912 returning some profits with shipping in passengers and then in 1913 southern pacific wanted to get in on the action and the competition from that and trucking roads really shut down the OS are so on the road closed down what happened to the road well it was used I as the stretch of highway 1 that connected Pacifica to Half Moon Bay in 1937 on that part of highway 1 was completed and it was a great way to traverse this terrain once again nature took a hand because in the winter 1938 the first slide came along that closed the section of highway 1 well then the show became very important to the military is that right thread in 1941 with the outbreak of war with Japan this area the same a tale coast was left completely undefended and so civilian and military patrols along this area double slide became the way that we would protect this area art wall most to the Army in the names of fighting in Europe and Asia and in 1943 the Army and Navy bill observation posts here on Devil's slide so that they could watch for invading ship to this is before the advent of modern radar so they would use that until the end of the war in 1945 when you goal past these as you driving down Highway 1 it said silent monument to the contributions that this Gary Mitchell look by Tony I such a heavy on the trail and I've been very excited to see you because I've been reading a book about the plans to the cemetery Coast and really getting impression that they're very unique along this part up the coast yes the plants are very unique here on the cemetery on this double slide they're actually starting at the top of the cliff with the coastal scrub plant community and then the plants actually get eroded down the side of the hill and get establish in the rock crevices and can grow on the side of the cliffs as well and also as the soil falls down erodes down the plants can get established in the lower areas where the soil has a little bit more buildup and these plants have adapted over thousands have years to be able to tolerate these conditions very unique to the cemetery Coast so Tony could you tell us what's on the place was he right right here sure we have California sagebrush in bloom right now and then below and we have the lesser tell it's in flour right now as well also over on the other side over here we have the gun plant the summer Plummer as well you can see the California Poppy our state flower the blue blossom see an author's the California phacelia it's one of the most prolific are flowering plants here on double slide the seaside AC occurs all up and down the cemetery coast as well it's a beautiful plant in this in the sunflower family the goldfields make a mass have color in the springtime mostly the annual Goldfields we have three different species said Lupin mostly the purple forms but we also get the yellow color forms as well and we have the metformin Lotus which is in the pea family the Indian paintbrushes another plant an annual plant that's very common along here it has a pool like some flowers structure we have the California Strawberry it has beautiful white flowers anger on the slopes as well as on the low-lying areas at different times of the year you'll see lots of flowering plants here and it's a beautiful garden just a beautiful garden hanging garden upslope garden downslope carton just one of the most beautiful gardens you can see on the senate a locust so the Hanging Gardens a double slide yes that's what I call them what are the wonders of the world it is look were on the north end of the trail and I'm here with professor Karen grow from San Francisco State University care we're standing here at at a wonderful spot on the trail that shows sedimentation going on can you tell us why there's so much color here well the color differences between the layers are because the darker layers are my head so very fine-grained sediment that and that's where the organic material tends to get concentrated so that's why they're dark in color the lighter color is say and so larger size settlement 7 like you would find on a beach the size that explains the difference in color here so what's amazing is the real distinct layers in the sediments what causes that yeah that's a a type have settlement reprocess that a we call turbidity flowers the dark colored the mud that sentiment that's just falling out a suspension through the water column for example settlement comes down a river it comes to the sea and the finer grained sediments are in suspension and they fall down to the bottom but once in a while there is an impetus such as an earthquake or a particularly big storm that moves sand bigger settlement along the bottom and I high-velocity turbulent flow and gives you a very distinct layer San now he said it was formed here no not in many ways actually they were first evolved formed in a marine environment so they were not up on land they were formed under the water deep marine environment and they were also formed in Southern California so 33 other commenters are so from here we're on their west side of the San Andreas Fault and this piece of land is continuing to move to the northwest with movements on the san andreas fault so we're creeping up towards alaska's at it we r at least on the side of the fault well this is really not the best place to build the road is that correct that is very much correct I these sedimentary rock are extremely weak because that the dominance the mudstone in the settlements they just crumble and particularly after a rain they just want two slides a geologist would have predicted that if you've got the right through here with Bay look with the North overlook at the trail back again with professor master of Skyline College and Mike understand that I'm this was a very important a area's history absolutely in 1769 I Gaspard de Porto la I was coming here assertive in advance guard for the mission systems that you know procera would build so famously and he came across the Ohlone Ian the other Indian tribes they were here on the coast are only a few thousand in their living here at the time and they decided that this was a good place to build and portal I was actually looking for Monterey Bay and missed it completely have to south of us a course rediscover San Francisco Bay and that was the beginning zev San Francisco and of course the mission that was built there and in 1776 they actually started using the limestone from the area right around double slide to make the whitewash for both the mission and the Percy do. that provided defense for the mission and then of course the Gold Rush changed everything kid yes it don't really change things in 1848 a course the first strikes are medical over by John Marshall John Sutter and of course the world rushdie and millions of people coming to this area and of course from here to the sea air is and it really brings out huge population into California just in time for California to become the 31st state which it did in 1850 and from then on California really became a place if promise a place a great business and of course double slide changed I in all kinds of ways and there's an editorial history to this course also right you're having to do with prohibition because of course after the 18th amendment was passed it became very difficult to procurer alcohol certainly legally but if you look around this is a perfect place to smuggle and to hide quantities of alcohol difficulty get to there's a sheer drop off to the Pacific are not very many people live here and it's easy to evade the federal authorities so great about it bootlegging happened here and no number for institutions would be serving illegal alcohol and running gentleman's clubs up until 1933 when probation was finally repealed and things in some sense went back to well this is like a very simple trail but there's a lot of history attached to it salute you really can't understand the history of San Mateo County completely without knowing something about double slide and that's why I'm glad we're here to talk about look run the middle portion of the trail on this is were double slide gets its name this is a its in areas really prone to slides and Karen I presume this is what the engineers tried to do keep it from sliding again yes I'll where humans put their infrastructure and places that are geologically an appropriate we then have to bring in the engineers to say stabilize this so we can continue to interact with that landscape those of us who have lived here for a while know that this has been a recurring problem %uh the road was closed for almost two years in the nineties their were problems continuously finally they decided that make the Tylenol and now we can enjoy this spot but they still have the structure the concrete structure to try to hold the rock in place they have tilt meters to try to cents any movement that occurs but you know it's one of those things where any geologist who would come along here would be yeah of course this is not gonna be a stable place to build a road in the first place the mud stone is very weak even the sandstone which is more resistant as highly fractured so prone to failure and the layers which were deposited horizontally are now all tilted and that makes them even more likely to to fall down so in California we do this a lot we've built houses on top at the San Andreas Fault we've built roads a and these very steep coastal places and and inland as well we're learning maybe a little bit that actually nature is always going nowhere and and so we need to think about what the geologic setting is before we do the building rather than after when we have to spend a lot of money to defects bank look house and thanks for coming on the trail today and can you tell us where the most common remembers you can see from the Spanish point sir the most common species is gray whale and there's a couple really good opportunities to see them throughout the year as they migrate along the California coast I wanna be up to new users around January the peak love their southward migration as they head down to ball hard to their birthing grounds and the other pic is around April and May as they head north to their feeding grounds and that's your best opportunity to see cow and calf pairs and those tend to hang really close to shore avoiding predators like workers are sure and this is one of the most amazing migrations in nature and we have an incredible opportunity because it happens right here every single year and I understand you can see other marine mammals to besides the gray whales yeah there's quite a few other cetaceans or will dolphin species and you can see here one of the more common ones is the bottle nose dolphin and both are regularly very close to shore and in small groups another one similar to the bar most often as the harbor porpoise their lot smaller than bottler softened and are usually solitary another bail email that you can see like the gray will is the humpback whale and their pretty much visible year-round able to october's their peak season they like to hang out a lot further up sure towards the shelf break a lot of times they put on showy displays like preaching and tail flapping is if you look at first Caroline Islands you might get lucky and see them there's several other species that are possible to see here the less common like Orissa's dolphin minke whales and or does what her skills are we looking at I'm the seals a year most likely to see our harbor seals and they often haul out on Saint Peter a rock in the distance I'm in intertidal rocks and they also pop here in spring there's a couple other pinnipeds or seal in feline species that you can see here and California sea lion sometimes call out on the small rocks around double side of or you'll see them swimming around and you might see a stellar sea lion there's a small recovery are on the Farallon Islands so we've seen them swimming by as well and you might even see in autre from time to time you might were kind about the northern extent of their rain so they're not very common but they have been seen here let the exciting to see with me so this is one the best vantage points for seeing remembers on the northern coast so what would you advise people to do it cannot hear bring your binoculars work towards a southerner the trail in this is where you see a lot of granite and can't you tell us how this credit is formed well it performs a it's an igneous rock and it forms deep beneath the earth when magma cools it would have formed many kilometers beneath the surface several miles if you well I'm by liquid rock magma cooling from a melt and so because its schooling beneath the surface if we can imagine this occurring way they need our feet it it 'cause slowly and so the crystals have a chance to achieve a large size and that's why we can actually see crystals of courts and other minerals in the granite but if we look at this entire good faith weakens the even more history than that we know this was formed deep under the surface but we see sediment sitting on top of it so that tells us that the granite was up lifted to the surface and when the granite was forming we were in a convergent plate boundary that is two plates from moving toward each other and so when you have that you have compressive forces and so then you can get I uplift I love you imagine abt pushing on something from both sides you can get it to up left and then they volcanoes that would abandon on the top but that the Magna would have been feeding those with the band eroded away and so a what we see is that the granite was up lifted to the surface and then in the marine environment the settlements the mudstone in the fans down were deposited on on top a bad I'm work the middle of a look at the trail and I'm here with lana from california audubon and and this is a spectacular place to watch birds isn't it it sure is Steve this is one of the best places now in a California coast to see seabirds and shorebirds this is one of the richest most productive marine environments in the world attracting predators from all over the Pacific including dozens of species of marine birds and what kinda Birju you see here depending on the time of the year you'll see everything from the city share water which comes here in huge numbers from New Zealand's their breeding grounds there to feel is rich in productive marine waters to the beautiful surf Scoter which breeds in alaska comes here in the winter to feed on herring roe and small fish all the way to the black Oystercatcher which breeds down here and may not go more than a kilometer and its lifetime there are many many speeches a bird's although their own individual stories there's the elegant tern and the here men's golf ball so which breed on one Island in the Gulf of California down in mexico come up here to feed and arrests in the wintertime and of course is the iconic albatross and two species that occur here other black-footed albatross which green Hawaiian fly thousands of miles to you find pray and bring it back to their young and the short-tailed Albatross which was presumed staying to nineteen fifties brought back from the brink of extinction and is being seen with increasing frequency here on the california coast all this really is a very special place to see sea birds it really is with the opening up this trail the public has access to birds couldn't see before it's a very accessible so I am very excited about this round what he refers to see you hi Steve it's nice to be here so we're standing on the on the trail above double slide rock they wanted you could tell me the significance that rock for the birds double side rock Kohls a nesting colony of common MERS and other sea birds which nests along the California coast here back in the nineteen eighties nesting calling out here was completely wiped out within just a few years mainly from boers been killed in gill nets an oil spills and we've been working for the last 18 years to the to restore that nesting colony surgery where these birds being protected well commerce a site called migratory birds in North America are protected under an act called the Migratory Bird Treaty Act in action after establish several decades ago to protect have burned migrating between Canada the United States and Mexico and even within those nations from harm because birds were being you know killed and slaughtered in such very large numbers historically you also involved in restoring the bird so how how does that work placing decoys that look like common murders up on the rock along with decoys serve that look like chicks and eggs that were placed on the rock to make it look like a real nesting colony and we also had a sound system that play the calls of Commerce in all this so was actually landed on the rock and placed upon the rock so that it would remain for several months at a time and that was put in place to actually attract the birds back to the rock so that they will come back and start messing again so judging from the birds I've seen on the rock it looks like the restorations been successful yes it has it's been very successful within the very first year we had birds nesting on the rock and we thought it would take maybe several years within five years we reach our 10 year goal which was a hundred breeding pairs we were able to remove all of the decoys and all the other social attraction equipment because it seem like that colony was now self-sustaining just within the last few years it looks like we have probably about the same numbers that we had before the colony was completely extirpate a back in the early nineteen eighties so if you come out here in the summertime you know the spring and summer you'll see double slide rock clearly just almost completely covered in nesting commerce so it's really exciting I'm we're near the southern into the trail again with professor grow from San Francisco State University and professor why is there so much fracturing going on here well these rocks have actually had a very tortured history their first problem was you at episode of contraction that lifted them up to the surface cent of course if you imagine applying pressure to anything it's kinda wanna crack especially a rigid body like this so we get a lot of cracking so its first thing was to get lifted up to the surface and a contract channel environment in probably an awful lot of these fractures are cracks occurred during that initial period I've up left for its crazy like you look at this in even down to the smallest level its fracture yet now I can see the really problems at once with even like these are all fractures in here though it's kids pervasively fractured its first step was to get uplifted to the service and a lot of things that happened that we don't really are to clear about but the what the other thing that we are very clear about is that starting about five to seven million years ago the San Andreas Fault as we know it today was born and this area west to the san andreas which we call the sole any enter an has been moving northwest relative to North America on the other side at that San Andreas Fault and so every time there's an earthquake a this piece of land goes another Meader or five meters or seven meters to the north to the northwest relative to what's on the other side so it has continued to be deformed by tectonic processes and continues to need a tortured life so this is the place to come if you wanna see some really twisted wrong look were staring to Southport allow the tunnel and I'm here is our Christian tucker and so I can you tell us the connection between the tunnel on the trail yes the trail here is actually all highway 1 a double slide when the tunnel was constructed one other benefits was that we have got access to this beautiful old road and it was turned into a trail now the story to tell really goes back a ways doesn't it it does this road has been a Bugaboo for decades in the winter and 1995 the road failed once again catastrophically leaving at stranded here for six months caltrans at that point was ready to build inland freeway bypass which the community had fought for years and years and years our elected representatives weren't willing to force caltrans to consider alternatives at that point we knew we had to take matters into our own hands well I remember how it took hours to go for one and %uh a highway to the other and then this became a real David implies struggled in it it absolutely did people were desperate their our life line was cut off but even despite that the coast fighters were unwilling to let that freeway bypass go forward and destroy Montero mountain really wanted a title alternative so we had no choice but to qualify an initiative for the ballot take matters into our own hands and we had a great time doing it we launched a campaign that spanned at the corners the fam it here County and beyond with I think tunnel bumper stickers marching in parade gathering signatures tabling at farmers markets and all over the county we actually even had one of the very first web sites created for political purposes way back in 1996 measure T the Double Play title initiative won in a landslide seventy-four percent of voters said yes we want tunnel a double slide well I campaign was a great success because now we have this beautiful total absolutely Steve it's a tremendous success because not only do we have the title that we have Montero mountain which is now protected as part of the Golden Gate National Recreation Area and we have this extraordinary beautiful trail for generations to come to enjoy I'm another chance in the wonders are the devil's slide tell you might want to come in a bass to yourself so cathy tell us what a bastard us here on the trail a trail ambassador is basically a customer service person we answer questions we remind people of the rules and we try to make their visit the most enjoyable and how they become a volunteer where you go to find out but thing about their two ways to do that you can ask the trail ambassador answer walking on the trail are you can check that cemetery county website and that will give me information on how to become a volunteer thank you for watching Pacific currents you can always see our shows on you too see you next time