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The unbelievable bathymetry of Mavericks




















The window for the Mavericks surf contest is open through the end of March, and at any time the selected contestants can be given 24 hours to head to California for the big-wave competition.

The contest has only been held seven times since 1999. The surf spot has only been known to the general public since 1990, after a photograph taken by a friend of Mavericks pioneer Jeff Clark (who first surfed it alone as a teenager in 1975) was published in Surfer magazine.

It is one of the largest and heaviest waves in the world (which makes the fact that Jeff Clark paddled a half-mile out to sea to surf it alone for years all the more impressive).

Surfline, itself a pioneer in the world of predicting surf, has an outstanding special feature presentation on the mechanics of Mavericks and the interaction of water and geology that produces its monster waves. It was produced and written by the late Sean Collins, the founder of Surfline, who was single-handedly responsible for changing the way surfers around the world check conditions before heading to the ocean, and published on November 16, 2011 -- only a month before he left this life at the age of 59.

The thirty-page analysis features beautiful aerial photographs and especially underwater bathymetry images showing the unique underwater terrain that channels wave energy from the largest northwest Pacific storms into the lineup at Mavericks. The word "bathymetry" (Greek for "the measurement of the deep") refers to the same science as topography, but underwater. Slide 8 of the Surfline analysis of Mavericks explains that:
Swells approaching Maverick's from the North Pacific will first pass over the continental shelf, and the distribution of swell energy along the coast will be determined by swell interaction with the topograph of the ocean floor (bathymetry). Swell energy will always turn towards shallower water (refraction), and swell direction and swell period will be contributing factors of how much the swell will refract.
Willard Bascom (1916 - 2000), a pioneering oceanographer and scientist and author of the excellent Waves and Beaches: the dynamics of the ocean surface (1964), whom we have met before in this previous post, explains refraction in that book by saying:
Refraction simply means bending. As waves move into shoaling water the friction of the bottom causes them to slow down, and those in shallowest water move the slowest. Since different segments of the wave front are traveling in different depths of water, the crests bend and wave direction constantly changes. Thus the wave fronts tend to become roughly parallel to the underwater contours. 70-71.
Underwater bathymetry imagery released in 2007 from the USGS and Cal State Monterey Bay revealed an amazing complex of dramatically curving reefs that channel the wave energy into the patch of ocean located off of Pillar Point (at the northern boundary of Half Moon Bay) where Mavericks breaks when the swell energy is powerful enough and the swell direction is right.

Slide 14 of Sean Collins' Surfline presentation of the Mechanics of Mavericks shows the critical portion of this underwater reef complex. The text on that slide reads:
The unique bathymetry extending about a mile offshore is the secret to the big surf at Maverick's. Recent side-scan sonar surveys by the USGS and the Seafloor Mapping Lab at California State University at Monterey Bay have revealed a very interesting swirling pattern of shallow reef that extends westward off Pillar Point. These swirling grooves in the reef off Pillar Point act like a huge magnifying glass to merge and focus extra wave energy from adjacent deeper water toward the shallower reef. The unique patterns in the ocean floor were created by long-term erosion and historic seismic activity of the local San Gregorio Fault system. Another possible cause is huge icebergs during the last Ice Age that may have helped to grind out these grooves -- a similar phenomenon that also occurred on the Hudson Shelf near New York.
The fantastic curving patterns can be seen in the NOAA/USGS imagery from this website shown in the diagram below. You can see how the deep channels on either side of the Mavericks lineup create refraction that cause waves to bend towards the shallower ridge in between the channels, focusing the wave energy.


























The origin of these graceful curving reefs, like other geological features on earth, invites various explanations. Like a popular mystery story (such as the stories of Sherlock Holmes, or Scooby Doo and the gang), there are explanations which generally fit into the popular assumptions and preconceptions of the powers that be, but these explanations may or may not stand up to scrutiny. The conventional explanations will generally involve tectonic forces, such as the idea that they were caused by "long-term erosion or historic seismic activity of the San Gregorio Fault system" cited above.

A more detailed example of a conventional explanation for such extreme curving geological features can be found in the Highly Allocthonous website of geologist Chris Rowan, where such plunging folds are explained as a "tale of orogenies past," in which tectonic forces lift parallel layers upwards (causing them to bend), and then other forces cause the fold axis to become tilted to some degree. When the tilted bent layers are sheared off, the folded layers present dramatic hairpin bends that represent the top of the uplifted layers. Mr. Rowan entitles his post "12 folds a-plunging" and provides numerous photographs of examples from around the world (all of them above the current ocean surface).

This blog post from professional geologist Michael Welland (author of Sand: the Never-ending Story, 2010) discusses the extreme curved reefs off the California cost near Half Moon Bay and links to the Highly Allocthonous post about "plunging folds" as a likely explanation for the bathymetry that gives rise to the waves of Mavericks. While the Highly Allocthonous post does not directly mention the reefs off of Pillar Point, the other examples it offers of "plunging folds" certainly makes it appropriate for Mr. Welland to argue that the mechanism described for the curving patterns in "12 folds a-plunging" are the same forces that created the bathymetry at Mavericks, and Mr. Welland concludes that the Pillar Point reefs are "clearly 'folds a-plunging' in the sea-floor off San Mateo County."

There are some significant details, however, which call into question this explanation for the origin of the severe curving reefs near Half Moon Bay. First, there is the question of the distinctive reef composed of concentric circles indicated by the white arrow in the imagery from CSU Monterey Bay below (this is the same imagery as that in the image above, but colored to indicate depth, with red being shallower and blue deeper water depths, and yellow indicating depths in between blue and red):

























It is difficult to imagine a scenario in which the concentric circles of the reef indicated by the arrow could have been created by uplifting of layers which were later tilted and sheared off.

In fact, the more one considers that explanation, the less satisfactory it appears in light of the reef patterns depicted in the sea-floor imagery. Note, for example, that the curves are clearly further apart at the point of greatest "hairpin turns" rather than closer together as we might expect if they were actually caused by tectonic uplifting.

Further, a close examination of the topography will reveal that the terrain in question is deeply scored and jumbled, and that it appears that wide bands have been "planed out" in this deeply scored terrain to create the graceful curves, but that some of the scoring lines clearly continue on the "other side" of the "planed out" bands.


























For instance, in the image above, the reader can examine grooves and scoring inside each of the circled areas which appear to have once belonged to a continuous piece of land which was later divided by some force that carved out a deep and smooth channel right down the middle. Not only are these channels significant to surfers at Mavericks (since they act to bend the wave energy towards the central ridge), but they are also important clues to the mysterious underwater terrain off the California coast.

The fact that something appears to have cut across the existing terrain and left deep grooves like this indicates flow of something -- the most likely suspects being liquid or viscid flows, either lava, glacial ice, or water. In each case, it seems clear that the terrain was not under the surface of the ocean when the lava, ice, or water carved these channels. The curving patterns are certainly indicative of flowing liquid or viscid forces as well*.

The image below from Google maps shows that the graceful curving reefs that create the Mavericks break are part of a larger patch of underwater ridges that stretch north of Pillar Point towards Montara and south into Half Moon Bay itself, but which are most extreme in the area of the Mavericks break.




















The darker area contains swirling patterns as well as "feathered" ridges that seem to end in a series of parallel points, resembling quite remarkably the patterns of the sacred moko of the Maori of Aotearoa (New Zealand).















The reader can click on the image to zoom in and see the details, or even better to visit Google and conduct a search on their maps for "Half Moon Bay, California" -- selecting the "satellite" imagery view rather than the "map" imagery view in the upper-right corner of the map will bring up the sea-floor images seen above.

Cruising along the Google Maps imagery up and down the California coast will show that the extended dark rough patch near Mavericks that resembles a moko in its swirling pattern may be more extreme than those found elsewhere, but that it is by no means alone. Other such patterns rise up out of the otherwise much smoother continental shelf at various points, including further north near Bolinas (also near a significant headland like Pillar Point accompanied by a wide bay) and further south near Morro Rock (again, a prominent headland and one which in this case features an obvious volcanic extrusion). See the images below.

















In the image above of the long dark scored reefs off the coastline near Bolinas, California, note the same hairpin curves and feathering found at Mavericks, and also note the very distinctive concentric circle pattern which is even more pronounced than the concentric ring pattern pointed out at Mavericks in the images above.
















The detail of the Bolinas pattern reveals very clear evidence that these "moko" patterns that seem to rise up at certain points along the California coast may be indications of volcanic activity in the ancient past. The concentric circles of the Bolinas "rough patch" form a complete ring (unlike those off of Pillar Point / Mavericks), and the USGS / CSU Monterey Bay imagery appears to indicate steeply beveled sides to the ring, giving it a very clear crater-like appearance.

Moreover, the deeply scored and darker sea-floor both here and at Half Moon Bay / Mavericks seems to indicate volcanic flow. The image below of another such "rough patch" off the coastline just south of Morro Rock (further south along the California Coast from Half Moon Bay, south of Monterey and Carmel and Big Sur) reinforces this conclusion:
















This kind of "washboard" terrain is very characteristic of ancient volcanic action, and is reminiscent of the terrain around Fort Irwin and the Mojave Desert that was discussed in this previous blog post. Note that again we find a volcanic-looking rough patch protruding from the otherwise smoother seafloor in the vicinity of a prominent headland -- Morro Rock sticks out into the Pacific in much the same way that Pillar Point does. It would be redundant to include an image of it here, but another such patch can be observed at Point Año Nuevo not far south of Half Moon Bay.

The interesting thing about these mysterious patches of heavily scored volcanic-looking ground is that they are surrounded by much smoother seafloor. In fact, looking at them for a long time will give the distinct impression that these rough patches themselves are partially filled up with the same thick silt and sand that blankets most of the adjacent seafloor. Let's return to the imagery around the Mavericks surf break and see.



















Just south of Half Moon Bay, at San Gregorio State Beach (where highway 84 intersects the Pacific Coast Highway or Highway 1) there is another small "rough patch" that clearly appears to be surrounded by silt. These patches are starting to give the impression that the entire ocean floor off the Northern California coast is really rough and washboard-like, but most of it is drowned in silt.

















A close-up look at the swirling ridges that lead in towards Mavericks gives the same impression: it appears that the long "feathered" ridges disappear into a deep layer of silt. In other words, these ridges probably continue on below the surface that we can see: they were formed first and then buried later in silt.

A closer examination of the concentric terrain feature near Mavericks will reveal the same thing: it is probably a crater very much like the one shown above at Bolinas, but since it is deeper and more deeply buried in silt, only the upper edges of the lip of the crater can be seen, and these do not form a complete circle above the silt as the crater at Bolinas does (the Pillar Point crater is probably a complete circle, but some of its lip is below the level of the silt that flowed in later).

What could explain these amazing terrain features? The conventional explanations are quite inadequate. The hydroplate theory of Dr. Walt Brown, however, provides a scenario which appears to fit the evidence quite satisfactorily.

We have already seen in previous posts that Dr. Brown's theory envisions the continents sliding away from the initial rupture (and the rapidly rising Atlantic floor, which sprang upwards after the escaping floodwaters removed enough sediment) and towards the newly formed Pacific Basin (which buckled downwards in compensation for the upward-springing Atlantic floor, "sucked" towards the Atlantic on the other side of the globe as if the underside of the Pacific floor were connected through the earth by long cables to the underside of the Atlantic).

The forward edge of the Americas would have experienced tremendous friction, enough to create heat sufficient to melt granite and produce massive amounts of magma, which later spilled out as immense lava flows (the Columbian basalts of Washington and the volcanoes of the Mojave area are two examples of evidence of this activity). Such friction and melting could explain the volcanic-looking deeply scored "washboard" terrain that we see in places along the front-edge of the drifting continent (the California coast and the continental shelf).

As the continents slid, they buckled and thickened. Later, when the continents finally ground to a halt, the floodwaters poured off of them towards the ocean basins, dumping massive amounts of sediments into the ocean basins. The waters pouring off the continents carved immense canyons as they cascaded over the edges of the continental shelves: the Monterey Canyon that was discussed in this previous blog post is one such canyon, as are the canyons of the Ganges Fan and the Indus Fan and the canyons found under the sea at the mouths of some of the largest rivers in the world such as the Amazon and the Hudson.

At that time, when those canyons were formed, the sea level was much lower than it is today (that's why those canyons could be carved by rushing water -- today they could not be carved because they are under the ocean). Note that another mighty submarine canyon yawns below the lip of the continental shelf just west of Mavericks and Half Moon Bay as well. Look just left of the large red letter "M" in the word "Mavericks" in the image below from this NOAA website about National Marine Sanctuaries in the United States.

























The sediment-rich waters flowing off of the continent may well have blanketed the washboard features so deeply that they only protrude in certain places along the California coast. It seems that at places where a large promontory (such as Morro Rock, or Pillar Point) shielded some of the silt flow, less sediments were deposited and some of the fingers of volcanic reef could poke through the silt. This silt likely hardened into sedimentary rock over the centuries before the sea levels rose to cover the continental shelves (the hydroplate theory explains that the continents were much higher relative to the seas immediately after the flood for some hundreds of years, before their great weight caused them to sink down and the ocean floors to rise).

The graceful curving patterns could have been caused by lava flow from the original lava activity that created the rough volcanic terrain, but it is much more likely that they were planed-out later while the continental shelves were still above sea level (based on the fact that some of the original grooves and scoring are interrupted by the broad channels that must have been scooped-out later).

These channels may have been carved out by glaciers which covered North America during the Ice Age that was caused by the temporarily higher continents and lower warmer seas (the warm oceans producing much more precipitation, which fell as snow and ice over the colder higher land masses). We know that glaciers reached these latitudes in California, as Yosemite Valley further inland is an obvious product of glacial carving.

An astute reader might wonder how the silt filled these glacial channels, if the silt was deposited by waters flowing off the continents right after the flood and before the Ice Age. It is possible that waters were trapped in the Great Central Valley of California long after the initial flood, later breaching and rushing out to the Pacific (just as other trapped waters later breached and carved the Grand Canyon, depositing tons of sediments in the Gulf of Mexico in the process, as Walt Brown explains in his book, which contains an entire chapter on the Grand Canyon).

The exact mechanism that carved the graceful channels in the original deeply-scored washboard is not certain at this time, but it appears likely to have been either glacial ice or sediment-rich water, and possibly later lava flows although this mechanism appears less likely*. The bottom line is that the mechanisms proposed by conventional geology appear quite inadequate, while there are several options which fit the general outline of the hydroplate theory. Note that the hydroplate theory was around long before the undersea images became available in 2007.

Thus, the incredible undersea terrain that produces the mighty waves of Mavericks appears to be yet another piece of geologic evidence that is very difficult to explain using conventional geologic theory, but which fits rather nicely within the predictions of the hydroplate theory.

The only question is, did the Polynesians (who gave the world surfing in the first place) somehow know about the distinctive undersea swirls that produce the gigantic waves at Mavericks, and incorporate these patterns into their tattooing? If so, perhaps they knew about this "undiscovered" surf break centuries before it became known again in the 1990s! But that is a mystery for another day.



* Note: since publishing this post, I have come to believe that hogbacks are the most likely explanation for these dramatic underwater features -- see this post, published 02/16/2012.

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Duke Kahanamoku

























August 24 is the birthdate of Duke Kahanamoku, born in 1890. Above is a photograph of the Duke, aged 21, about 100 years ago. An Olympic gold medalist in swimming, Duke's greatest legacy was his towering role as the first real international ambassador of surfing. He is almost singlehandedly responsible for launching the ancient Polynesian "Sport of Kings" in California and Australia and for generously sharing the stoke where ever he went.

Here is a link to a website describing the first recorded western account of surfing by a lieutenant of Captain Cook on a voyage to Hawaii -- subsequent pages describe the role of Jack London, George Freeth, Alexander Hume Ford, and especially Duke Kahanamoku in reviving the sport of surfing and then spreading it worldwide.

Below is a video showing early footage of Duke surfing at Honolulu with Diamond Head in the background.


The video below describes Kahanamoku's 1915 visit to Australia, where his surfing demonstrations fell on extremely fertile soil and can be directly credited with launching that country's well-known fervor for surfing.



Like other legendary Hawaiian watermen, Duke Kahanamoku was also an actual lifesaver, and once dove into the waves repeatedly to save several fishermen in distress when their boat capsized in heavy surf off of Newport Beach in June of 1925.

Surfers everywhere should be grateful to Duke Kahanamoku for his efforts to spread the ancient Polynesian art of surfing beyond the shores of Hawaii in the best tradition of Aloha.

Peace.

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Happy Birthday to Shaun Tomson


August 21 is the birthday of Shaun Tomson, a groundbreaking surfer with an unmistakeable style.

He has been featured in posts on this blog previously here, here and here.

Above is a link to the iconic 1978 surf movie Free Ride, which features Shaun Tomson and Rabbit Bartholomew along with Mark Richards, Larry Bertleman, and other innovative surfers of the era. Even thirty-three years later, some of the surfing scenes in this movie rival anything that has been captured on film.

The movie's long surf sequences and many slow-motion sequences allow viewers to really study the surf style of the different surfers, which completely changed surfing and which is even more impressive considering the boards they were using at the time.

In the movie, Shaun explains: "I've got this sort of standard in my head of what I think good surfing is, and I always try to exceed that standard."

Happy birthday to a true living legend of surfing -- may he long continue trying to exceed his own standard!

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Bodhi and Point Break



August 18 is the birthday of the late Patrick Swayze, born this date in 1952.

Twenty years ago, as my class was just graduating from West Point, the movie Point Break hit theaters in the United States, starring Swayze in the role of Bodhi.

Having spent almost every free moment in the previous three-plus years skydiving in California, New York, Florida, North Carolina, and Arizona, and having started to surf before I'd learned to skydive, the release of Point Break made a big impression on me in 1991.

Whatever its flaws (does it actually have any flaws?), the movie was probably the most successful fictional depiction of surfing ever made, and took a completely different direction from what had been portrayed on film before. Swayze's portrayal of Bodhi was masterful and broke the mold of Hollywood's typical depiction of surfers. He also did many of his own skydiving scenes and went to the island of Kauai to learn to surf prior to the making of the movie.

While it is still only August 17 here in the US, it is already August 18 in Australia, where the final scene of the movie is supposed to take place, at Bell's Beach (the scene was actually filmed in Oregon), and since surfers there might want to pause to appreciate Swayze's contribution to surf culture as well, this post will go live on Australia's August 18.

Respect.

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UFOs at Flagler Beach, Florida?



Here is a video from a "local news" station in Flagler County, Florida, reporting on an unidentified ball of flame which several Flagler Beach residents saw earlier this week at about 11 pm, descending towards the Atlantic Ocean.

According to the news reporters, the FAA was notified after several citizens called local law enforcement, and the FAA has confirmed that no aircraft were in the vicinity, and thus the possibility that the citizens saw a plane in distress has been ruled out. Furthermore, the Coast Guard apparently conducted a search of the waters off of Flagler Beach beginning at about 11:45 pm and called off the search at about 8am the next morning, having found nothing.

This has led some to speculate that the ball of fire could have been some kind of UFO. Others are dismissing it as nothing more than a floating Chinese lantern, as described in the news story below:



This particular story is of personal interest to me, as I have fond memories of a day of skydiving from the Flagler County Airport while in the area for a parachute meet during my years on the West Point Parachute Team. The photograph below shows my teammates and I with the beach and the ocean in the background, taken in December 1989 (your faithful author is the individual on the far left of the formation as you face it, wearing a black sweatshirt).



















The area covered in this photograph can be seen in the Google Map, below (the arrows indicate the approximate line of sight and edges of the photographer's field of vision). You can see the line of Interstate 95 cutting across a diagonal near the lower left corner of the photo, and the line of Highway 100 / Moody Boulevard running towards the ocean in the right side of the photo and taking a bend to the left as it nears the coastal town of Flagler Beach. The pier in the videos above is located almost precisely along the line of Highway 100 / Moody Boulevard, to the right of the rightmost skydiver in this photo.

























The presence of a skydiving community near Flagler Beach gives rise to another possible explanation for the activity discussed in the videos above. Rather than a rogue Chinese lantern, perhaps the mysterious light was the result of the following scenario: a prank-loving skydiver took a Cessna up to about 11,000 feet and jumped out, activating pyrotechnic flares or powerful lights attached to his boot or lower leg either while in freefall or after deploying his parachute. He could then have spiraled down for a beach landing, collected up his gear, and been out of there without leaving a trace for the Coast Guard to find when they began their search an hour later.

In any case, I did not notice any alien activity on any of the skydives I made while in Flagler County in 1989. I did notice a pretty nice-looking wave in the first video above, at exactly the 1:00 mark. None of the surfers in the video are actually near that wave, which does lead me to believe that something strange was going on in the area around Flagler Beach when the video was taken.

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Moon, turn the tides . . . gently, gently away



Previous posts have discussed the moon's orbit around the earth and the cause of the different phases that we observe from our vantage point on earth's surface. We noted that the moon's tilted orbit versus the plane of the ecliptic gives rise to the two lunar nodes (where the moon's path crosses the ecliptic), which were included along with the visible planets and the sun and moon themselves to give the nine worlds found in many ancient cosmologies, including many shamanic cultures in which the shaman's tree by which the shaman ascends to the celestial realm may have nine branches.

The moon, of course, also creates the tides, very important to surfers and to the ancient navigators who traveled the earth's oceans alike. Above is an early animated film from pioneering American animation studio Bray Productions, which contains a very good explanation of the forces which cause the tides. Today's viewers may be slightly impatient at its slow pace, but be patient and enjoy it: it's really quite worthwhile. The fact that this is a silent movie means that it was probably made prior to 1928, when Walt Disney amazed and delighted audiences by adding coordinated sound to his animated clip Steamboat Willie. Bray Productions was founded in December, 1914 and began moving heavily into educational animated productions after World War I (when their successful training videos created great demand for more), so the film above may have been produced between 1918 and 1928.

As the film illustrates, the tidal bulge on one side of the earth is fairly easy to understand (being caused by the gravitational pull of the moon), but the tidal bulge on the other side of the earth is actually caused by the fact that the moon pulls earth as well, actually pulling the earth enough to create the bulge on the other side. The tides take place as the earth itself rotates underneath this enormous "standing wave," a wave so large that its two crests are separated by half of the circumference of the earth itself.

This is easier to conceptualize if we realize that the earth and moon actually form a pair which impact one another, rather than the moon simply orbiting a stationary earth that is not affected by its orbiting partner. The video at the beginning of this previous post (which discusses the theory that the sun is actually part of a very distant binary pair) contains good animation illustrating the motion of two bodies in a binary orbit. While earth's motion in space is of course primarily impacted by its path around the sun each year, the motion of the moon around the earth each month tugs on it slightly as well (just like two dancers or ice skaters who are spinning around one another joined by their hands; we could imagine the earth as a dancer which is going around the sun but which at the same time is spinning a smaller dancer around it in a circle, their outstretched arms grasping one anothers' hands representing gravity, and this motion creates a slight pull on the earth as it goes around its larger path). This pulling on the earth creates the tidal bulge opposite the moon.

The video also illustrates the cause of spring tides and neap tides. The gravitational pull of the sun creates a slight bulge in the ocean as well. When the moon and the sun are aligned, as in a new moon or a full moon, the bulge created by the sun is added to the bulge created by the moon, causing a much higher bulge and greater tidal variances. These are known as "spring tides" (not related to the season known as spring). When the moon and the sun are not aligned, the bulges are out of phase, reducing the difference between high tide and low tide. These are known as "neap tides" (a word originating in Old English).

The action of the tides is slightly more complicated than the description above and the video would indicate, however. For one thing, we might ask why the moon is more important in the tidal action than the sun. Willard Bascom (1916 - 2000), pioneering oceanographer and scientist and author of the excellent Waves and Beaches: the dynamics of the ocean surface (1964) as well as studies on Polynesian history, explains further:
It remained for Isaac Newton to discover the law of gravity, which holds that the gravitational attraction between two objects is directly proportional to the square of the distance between them. From this relationship it can be shown that the gravitational attraction of the sun for the earth is about one hundred and fifty times that of the moon. The tremendous mass of the sun more than makes up for its much greater distance. But the moon is the primary cause of tides. Why?

The answer is that the difference in attraction for water particles at various places on the earth is far more important than total attraction. That is, because of the moon's very nearness (average only 239,000 miles) there is a big difference in the gravitational attraction from one side of the earth to the other.

The water on the side of the earth nearest the moon is some four thousand miles closer to the moon than the center of the earth; the water on the far side is four thousand miles farther away. The sun, however, is ninety-three million miles away, and a few thousand miles one way or the other make comparatively little difference. Thus, the sun's gravitational force, although far larger, does not change very much from one side of the earth to the other. So the moon is more important in producing tides. 84.
Mr. Bascom also explains that the fact that the moon is rotating around earth in the same direction that earth is turning causes the "tidal day" to be slightly longer than twenty-four hours (by about fifty minutes), because the moon's motion means that any point on earth must go slightly further than a full rotation in order to come underneath the moon again. He also explains that the friction of the earth as it rotates beneath the ocean pulls the ocean along, such that the tidal bulge is not aligned directly beneath the moon as it would be if earth's rough ocean basins were frictionless instead. Because of this friction, the tidal bulge is carried forward by the rotation of the earth and is slightly ahead of the moon; "in consequence a point on earth passes beneath the moon before high tide" (85-87). In other words, as earth rotates, the point on earth will pass the moon before it gets to the tidal bulge that the rotation of earth has carried to a point ahead of the moon that is causing it.

There are still more complications that impact the motions of the tides. Because the moon's orbit is elliptical rather than circular, the moon is closest to earth at one point (perigee) and farthest at another (apogee), which creates a change in distance that impacts the tides (a discussion of the impact of an elliptical orbit on earth's path around the sun is discussed in this previous post).

Mr. Bascom explains:
At perigee, the nearest point in its orbit, the moon is fifteen thousand miles closer; at apogee it is that much farther away. This change in distance (and therefore in the attractive force) causes tides that are, respectively, twenty percent higher and lower than average. Perigee is reached once an orbit (once a month) and only rarely does this coincide with the in-phase alignment of sun, earth, and moon. But at least twice a year both effects exist at the same time -- that is, a full moon or a new moon exists at perigee. Then the perigee tides add to the spring tides to produce the highest tides of the year. 88
Mr. Bascom also explains that, while most points on earth experience two tides a day, there are a few places which only have one high and one low a day. The reason for this is that the moon's orbit takes it to points where it is "in the tropics" -- pulling the tidal bulges to an inclination that runs across the equator, such that one bulge is more pronounced in the northern hemisphere and the other bulge (on the other side of the earth) is more pronounced in the southern hemisphere, on the other side of the equator. The diagram below will help one visualize why this would happen. This phenomenon explains why one high tide is usually much higher than the other at any point on earth, and why in some extreme locations there will only be one high tide per day.


















Mr. Bascom's excellent book discusses much more than tides, and is highly recommended for everyone interested in waves, beaches and the ocean. For more about Mr. Bascom, you can check out a 1966 article in Life magazine about him on the web here (the article, "Trailbreaker of the Deeps," begins on page 108 of that online magazine; there is a table of contents on the left-hand side of the magazine which contains a link that will take you to the beginning of the article).

I myself learned about Willard Bascom from the pioneering surfboard shaper "Bob Smith," who has a blog here. His book on surfboard shaping, The Basics of Surfboard Design, is an excellent resource for surfers and shapers, and it gives due credit to the wonderful wave analysis of Willard Bascom.

Below is a video of the classic Jimi Hendrix song "Moon, turn the tides . . . gently, gently away," from his album Electric Ladyland (1968). Note that the lyrics, which do not come in until near the end of the song, include, "I can hear Atlantis, full of cheer . . ."



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Shaun Tomson: The Light Shines Ahead


Here is a link to a video of a very moving talk by Shaun Tomson, a superlative surfer and a very encouraging and giving human being, in which he shares a deeply personal part of his family's story with the world.

If you haven't listened to it yet, you should stop reading now and do so.

Yesterday's post discussed Mr. Tomson's film Bustin' Down the Door, and a few of the many layers of issues regarding the shared human experience which that film engages and enables its viewers to consider. The talk above, which Mr. Tomson gave on December 22, 2010, provides a much more intimate perspective on the words shown on the screen at the end of the movie, which were written by Mr. Tomson's son, Mathew.

It is an unforgettable talk.

At the end, he encourages each of his listeners to imagine what would happen if they would take just thirty minutes each week to sit inside a "sacred story circle" to share their story and their light with someone else. The reference is to a poignant memory he shares with us about a time he shared with his son inside just such a circle.

It is worth noting that there is very ancient precedent for the circle that his son created and shared with his dad, and which his dad then shared with the world.

We noted in this previous post the resemblance that many historians have pointed out between the activities of the ancient Celts and Druids (prolific builders of stone circles) and those of the ancient Hebrews.

The poet, historian and playwright Thomas Moore (1779 - 1852), considered the National Bard of Ireland, wrote a four-volume History of Ireland (published between 1835 and 1846), in which he discussed the ancient precedent of the sacred stone circle, as well as the connection between those of the ancient Hebrews and those of the ancient Druids, saying:
No less ancient and general, among the Celtic nations, was the circle of upright stones, with either an altar or tall pillar in the centre, and, like its prototype at Gilgal, serving sometimes as a temple of worship, sometimes as a place of national council or inauguration. That the custom of holding judicial meetings in this manner was very ancient appears from a group which we find represented upon the shield of Achilles, of a Council of Elders, seated round on a circle of polished stones. The rough, unhewn stone, however, used in their circular temples by the Druids, was the true, orthodox observance of the divine command delivered to Noah, "If thou wilt make me an altar of stone, thou shalt not make it of hewn stone" [. . .]. Volume 1, pages 37-38.
Thus the sacredness of such stone circles is very ancient indeed.

The "prototype at Gilgal" to which Thomas Moore refers above can be found in Joshua 4:20-22 (and note that the verses contain a strict command for the sharing of sacred stories between fathers and children).

Mr. Tomson is one of my personal heroes, not only for his surfing but also for his stature as a human being, in much the same way that he describes the great Duke Kahanamoku as his personal hero growing up. Mr. Tomson's surfing can be used to understand an important principle about the earth's orbit around the sun, through the video attached to this previous blog post. We should all be grateful for his willingness to share his story.

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