Submarine canyon formation theories

[CharlieO]

Moderation note: this thread formerly appeared in the thread 13779. It has been moved to a new thread to keep its former thread on-topic, and encourage concentrated discussion on the subject of how undersea canyons and similar features formed.

 

FREEZTAR: New method for communicating, until phone system is serviced on Monday, which may be doubtful as we are expecting snow again. Drive to Greeley to take wife to clinic, while there go to nearby library and use their computer to surf internet, download items of interest on SD camera chip ASAP, return home and wait 30 minutes for this page to load, then down load the following regarding. Works for me.

 

RE: My claim that river beds exist under the sea and far out into the oceans, therefore sea levels must have been far lower in the past.

 

Regards, CharlieO

 

Submarine canyons: a 50-year perspective

 

Submarine canyons: a 50-year perspective

F.P. Shepard has devoted most of his professional life to the study of submarine canyons. These great canyons, some cut through thousands of feet of hard crystalline rock, dwarf the largest land-based canyons. No wonder Shepard was fascinated enough to spend his life collecting data and weighing possible explanations. After 50 years, he has concluded that these colossal submarine features have no single cause. Subaerial erosion, turbidity currents, submarine slumping, and faulting have all played roles.

 

Anomalists will be most interested in Shepard's insistence that the evidence shows that subaerial erosion has played a major part in carving out the submarine canyons. This explanation is definitely frowned upon by most geologists because the Pleistocene sea levels dropped only about 100 meters according to current thinking. How could subaerial erosion account for canyons several thousand feet below present sea level? Shepard persists; the evidence is there. The continental margins must have risen and then sank back! He also points out that the Mediterranean seems to have dried up in recent geological times. Could the major oceans have dropped thousands of feet in a similar fashion? Shepard doesn't intimate this, saying only that the submarine canyons still present puzzles.

 

 

 

THE LATELY TORTURED EARTH: PART V: RIFTS, RAFTS AND BASINS: 23.Canyons and Channels

 

Landes writes: "What manner of logic allows us to accept evidence, such as marine strata, of a sea-level far above present datum of 25,000 feet, but causes us to run from evidence of a sea-level depression of 25,000 feet?... What is so sacrosanct about current sea level?" The trouble here is that the logic is not good enough. One ought not to have indulged in the notion of a sea-level 25,000 feet higher because of the marine fossils up there, especially while he was laughing over Noah's Ark. Furthermore, the present sea bottoms and therefore sea-levels can be depressed by another 25,000 feet, but again no mechanism is perceived.

 

He, and others, should be asking the deeper questions: "What are these deluges that humanity has been clamoring about since the dawn of history?" "Must every drop of water bear the holy stamp, 'Made on Earth'?" "How long does it take a pre-designed fracture trough to make a river channel, complete with fractured and non-fractured meanders? .... What is so sacrosanct about the ocean basins having always been filled with water?" I think that we have progressed far enough along in this book to dispose readily of the submarine canyon problem. The canyons were instantly created great river courses that rushed down, first, precipices, then, steep slopes, then gradual slopes, into the ocean basins that were only partly filled with water. Drainage of the water-logged continents and successive deluges filled the ocean basins to overflowing. As the seas encroached upon the rivers, the rivers were also receiving far less water to give to the sea. The underseas box-like, sluice-like channels ended their careers as turbulent rivers within perhaps two thousand years.

 

They have not filled with sediments. Gross, in his Oceanography, says that submarine canyons would soon fill up if they were not being emptied by turbidity currents. Geology has invented some bizarre mechanisms to circumvent catastrophism and here is one of them: turbidity currents. They have never been actually observed; they are "intermittent;" they are caused by earthquakes; they have speeds of 20 km/ hr; they account for anomalous continental sand and fossils found on the ocean floor. A rare study assigns them credit for having broken a trans-Atlantic bottom cable. (Still, no one denies seismism.) Would not such currents act as bulldozers instead of sweepers, and fill, rather than clean out the canyons? Our quantavolutionary theory is adequate for all that bespeaks turbidity currents, including the oceanic sands and fossils.

[Turtle]

... The continental margins must have risen and then sank back! He also points out that the Mediterranean seems to have dried up in recent geological times. ...

.

 

This drying up is understood through plate tectonics. (Scroll down to find pertinent data)>>

Plate Tectonics and Earth History

...By 6 million years ago' date=' Spain and Africa collide, raising a mountain barrier and sealing off the western end of the Mediterranean. River inflow is not enough to maintain the level of the Mediterranean, which dries out.

However, rivers flowing to the Mediterranean can cut below Atlantic sea level. Eventually one does, and Atlantic sea water starts flowing in, cutting the Strait of Gibraltar and filling the Mediterranean. ...[/quote']

 

 

Landes writes: "What manner of logic allows us to accept evidence, such as marine strata, of a sea-level far above present datum of 25,000 feet,...

 

The manner of continental uplift logic allows marine strata at 25,000 feet. Some slow, some not so much. >> ;) :eek_big:

 

WHALE FOSSILS HIGH IN ANDES SHOW HOW MOUNTAINS ROSE FROM SEA - New York Times

Scientists have found fossils of whales and other marine animals in mountain sediments in the Andes, indicating that the South American mountain chain rose very rapidly from the sea.

 

The rare assemblage of fossils, recovered on an expedition by the American Museum of Natural History to a remote plateau in southern Chile, is expected not only to illuminate an obscure epoch of animal evolution but also to document the rise of the Andes mountains in the past 15 million years. ...

[CharlieO]

Gentlemen,

 

Although living in a rural area and frustrated by a poor dial-up connection, I have resisted satellite service due its cost being five times higher than the DSL service I have been promised "soon," if I ever get it. However, due to Hypography sending me emails of your responses, I discovered I am able to answer them as "Mail waiting to send." Then I cut and paste the text into your website. Certainly improves my admittedly poor spelling and improves overall response time. Who says you can't teach an old dog new tricks?

 

Still unable to surf the Internet for answers to thoughtful questions from many, I am very appreciative of the education provided directly by CraigD and others, as well as the thoughtful questions which have prompted me to learn more than I even did in college, in the same amount of time.

 

For now, I'll have to admit I've been depending on memory of research done 50 years ago and college courses taken 40 years ago. I'm sure my memory may not be as accurate as it should be, nor do I have useful references available. Therefore, I'll have to put my search for the "exact" amount of hydrogen escaping into space on hold for now. I still believe there is a hydrogen reservoir within Earth from whence the hydrogen effuses, albeit perhaps insignificant.

 

Meanwhile, FREESTAR has raised an issue once dear to my heart, the age of oceans.

 

About 40 years ago, in a graduate course on land form evolution, I foolishly suggested consideration of the alternative concept of ocean floors being evidence of Earth's expansion and contraction instead of subduction. Nothing new. This idea has been around for centuries. Yet, the response from academics was like I claimed the Virgin Mary was a whore.

 

However, considering the ocean floors are fairly young and the continents are very old, could there be any alternative to subduction? I thought there might be, especially if the core were metallic hydrogen and its expanding hydrogen effusion might expand the Earth.

 

So I went to a garage sale and bought a used basketball. Taking the rubber bladder out, I attached a dry air injection needle and a 12 volt air compressor hose to that. I hung it from a garage rafter and firmly filled it, substantially expanded. Then I painted its surface with dry wall paste and allowed that to dry. When I expanded it with more air, the paste cracked and separated into fairly large pieces; probably because the paste was not of uniform thickness. Still, I thought I had a good demonstration of sea floor spreading.

 

However, when I let the air out, the bladder became smaller, the pieces moved together and their edges crushed into each other, producing micro-mountain ranges. Then I repeated the process several times, each time producing even higher micro-mountain ranges on even smaller pieces when the bladder was contracted and then even wider separations between the pieces when the bladder was expanded. Now, I thought I had an even better demonstration of sea floor spreading on a cyclic Earth.

 

You can imagine the response when I presented the demonstration results to the class, complete with photos. Some students walked out, others said it made sense. The professor, to his credit, said it was interesting, but hardly proof of a hydrogen core blowing up the earth.

 

So I went back to the drawing board. It is common knowledge that rock layers can be seen crumpled and folded. I took a series of geologic maps and roughly estimated how large their areas might be if these folded layers were stretched out flat. This added more surface area than I expected. So I "stretched" out all the continents, especially their mountain ranges, and found this created a much larger surface area than seen in continents today.

 

I drew these stretched out continents to scale on pieces of truck tire inner tube rubber and used rubber cement to affix them onto my trusty basket ball bladder. Took several tries to adjust the pressure to provide the proper bladder diameter, but I soon had the continents nearly touching EVERYWHERE on the bladder's surface. Clearly, to me at least, ALL the continents were once much larger in size and were also connected together, everywhere on a not too much smaller Earth.

 

This made more sense to me than a Pangea located as a lump of crust on only one side of Earth. So I reported my findings to the class and modestly named the fully enclosing Proto-Earth's continental crust, "Odenland." Again, the response was as you might expect. Some walked out and some said it made sense.

 

I went ahead and sent the results of my efforts to various publications, with no response. Not even rejections. So I self-published my findings in a monograph on Odenland and the hydrogen core, with copyright, and sent this to a hundred or so universities and oil companies. Again, no response.

 

So, until recently, I haven't mentioned Odenland and a cyclic sized Earth to anyone for over 40 years. Your response, if any, may be interesting to say the least.

 

Regards, CharlieO

[REASON]

.....So I went back to the drawing board. It is common knowledge that rock layers can be seen crumpled and folded. I took a series of geologic maps and roughly estimated how large their areas might be if these folded layers were stretched out flat. This added more surface area than I expected. So I "stretched" out all the continents, especially their mountain ranges, and found this created a much larger surface area than seen in continents today.

 

I drew these stretched out continents to scale on pieces of truck tire inner tube rubber and used rubber cement to affix them onto my trusty basket ball bladder. Took several tries to adjust the pressure to provide the proper bladder diameter, but I soon had the continents nearly touching EVERYWHERE on the bladder's surface. Clearly, to me at least, ALL the continents were once much larger in size and were also connected together, everywhere on a not too much smaller Earth.....

 

Regards, CharlieO

 

I gotta admit, Charlie, you sure are relentless in your efforts to prove this hydrogen core theory of yours.

 

Your experiment suggests that we are currently in a period of expansion. How does this explain the existence of subduction zones along one side of a continental plate, and rifts along the other. During an expansionary period, would not the expansion be occurring in all directions revealing only rifts, and conversely during contraction periods only subduction? With your theory, how could you have both occurring simultaneously?

 

Also, this concept doesn't explain the substantial difference in the space created by the Pacific Ocean compared to the Atlantic, say for instance. The stretching, as you suggest, would have to be significantly larger along Western North and South America, and Eastern Asia. How do you propose this is accounted for in your continental expansion/contraction theory, considering you don't buy the Pangaea super-continent theory?

 

When you say, "not too much smaller Earth," how much smaller are we actually talking about according to your sample experiment? What's the actual ratio you came up with?

 

I'm not sure you'll be able to stay on your feet on this one. This is teetering on the edge of "Strange Claims" land. Good luck.

[Buffy]

If I understand you correctly, you are stating that canyons cannot form underwater. What is the basis of this claim? You can actually do some simple table top modeling of this with sand overlaying clay in a box: even if it is submerged, a river flow will continue to cut canyons far out into the ocean without it being exposed.

 

Dating of layers in these oceanic river canyons (in my own backyard we've got the Sacramento/San Joaquin river system scouring out the quarter-mile deep canyon at the Golden Gate, and even deeper out into the Pacific, as well as an amazing subsurface canyon where the Salinas River discharges into Monterey Bay) shows that the creation of these canyons occurred during a period when it is known with certainty that they were submerged.

 

Can you clarify?

 

When beholding the tranquil beauty and brilliancy of the ocean's skin, one forgets the tiger heart that pants beneath it; and would not willingly remember that this velvet paw but conceals a remorseless fang,

Buffy

[CharlieO]

BUFFY: you wrote, where the Salinas River discharges into Monterey Bay shows that the creation of these canyons occurred during a period when it is known with certainty that they were submerged.

 

Regretfully, I cannot find any physical evidence of the above, other than varied opinions promoting Turbidity currents, which have never been recorded to actually exist; as far as I can find. However, I continue to be handicapped by poor Internet connections. Plus, this subject, the origin of submarine canyons, is only slightly related to the subject of this thread, seeking the amount of hydrogen effusing into space. Perhaps the origin of submarine canyons might be worthy of a new thread?

 

Also, I must apologize again for delay in response. Terribly busy in home of late and unable to down-load or surf the Internet for references without tying up the phone line for long periods during the day due to a very poor connection. So, staying on line for long periods is a no-no of late. Still waiting for DSL service, still promised soon.

 

Anyway, in regard to submarine canyons, they seem to me and many others far more qualified to be the result of sea levels becoming much lower in the past, allowing river flows to extend considerably further than the continental shelves' sea shores of today. That these enormous canyons, many greater than the present Grand Canyon, were somehow created by the widely assumed Turbidity currents seems to me only another assumption by those determined to believe Earth has changed very little over the eons.

 

In fact, ocean currents at the mouths of most rivers usually flow at right angles to the exiting river current, spreading river sediments away from the submarine canyons now extending onto the ocean floors. Hardly any possibility for these river currents to produce any of the water flow erosion features which can be seen in submarine canyons.

 

In fact, in many areas, your Monterrey Bay for example, the water flow within its off shore submarine canyon is largely upwelling and a source for the great amount of nutrients found there, which supports the local fishing industry. Hardly any evidence for any fast moving Turbidity current to have ripped out its great canyon in the continental shelf. On the contrary, its submarine canyon shows evidence of subaerial river flows, with varied level water flow terraces cut into the sides of the canyon by tremendous amounts of subaerial river water rushing across a dry landscape.

 

The following may also be of interest.

 

Regards, CharlieO

 

 

THE LATELY TORTURED EARTH: PART V: RIFTS, RAFTS AND BASINS: 23.Canyons and Channels

 

I claim that the finding of graded clastics and misplaced (shallow-water) faunas deep beneath the sea is not prima facie evidence that they were carried there by turbidity currents: that the finding of cobbles does not prove that they were transported by submarine landslides; and that photographs of ripple marks lying at a depth of 4,500 feet do not necessarily mean that they resulted from current action operating at depth... I likewise believe that deep-sea- floor current ripples, like the truncated seamounts, are relics of shallower water.

 

Landes writes: "What manner of logic allows us to accept evidence, such as marine strata, of a sea-level far above present datum of 25,000 feet, but causes us to run from evidence of a sea-level depression of 25,000 feet?... What is so sacrosanct about current sea level?" The trouble here is that the logic is not good enough. One ought not to have indulged in the notion of a sea-level 25,000 feet higher because of the marine fossils up there, especially while he was laughing over Noah's Ark. Furthermore, the present sea bottoms and therefore sea-levels can be depressed by another 25,000 feet, but again no mechanism is perceived.

 

Scores of impressive submarine canyons extend the courses of rivers around the world. The idea that they were once active as rivers was resisted for a generation. In 1936, Francis P. Shepard could formulate the predicament, which still stands unresolved:

Investigations of submarine canyons carried on for a number of years with the cooperation of the Coast and Geodetic Survey, the Geological Society of America, Scripps Institution and other organizations have revealed that these sea-floor canyons have all the characteristics of river canyons and are distinctly different from fault valleys. Also tests of the idea that the submarine canyons might be the product of currents have produced negative results so that they have evidently been cut by rivers. The significance of this sub-aerial erosion on the present sea-floor is particularly disturbing, since the submarine canyons extend out to depths of from 2,000 to as much as 10,000 feet and are found off practically every coast of the world.

 

 

Submarine canyons: a 50-year perspective

 

Submarine canyons: a 50-year perspective

 

F.P. Shepard has devoted most of his professional life to the study of submarine canyons. These great canyons, some cut through thousands of feet of hard crystalline rock, dwarf the largest land-based canyons. No wonder Shepard was fascinated enough to spend his life collecting data and weighing possible explanations. After 50 years, he has concluded that these colossal submarine features have no single cause. Subaerial erosion, turbidity currents, submarine slumping, and faulting have all played roles.

 

Anomalists will be most interested in Shepard's insistence that the evidence shows that subaerial erosion has played a major part in carving out the submarine canyons. This explanation is definitely frowned upon by most geologists because the Pleistocene sea levels dropped only about 100 meters according to current thinking. How could subaerial erosion account for canyons several thousand feet below present sea level? Shepard persists; the evidence is there.

 

 

 

subaerial erosion (geology) -- Britannica Online Encyclopedia

 

submarine canyon formation theories

 

For years the origin of submarine canyons has been the subject of much debate among investigators. Various ideas have been proposed, but prevailing theory favours subaerial erosion as the starting point for a good number of undersea canyons.

[CraigD]

… Plus, this subject, the origin of submarine canyons, is only slightly related to the subject of this thread, seeking the amount of hydrogen effusing into space. Perhaps the origin of submarine canyons might be worthy of a new thread?

A good idea, I think. If you’d like, let me know, and I’ll de-clutter this thread by moving posts on this subject to a new thread.

Regretfully, I cannot find any physical evidence of the above, other than varied opinions promoting Turbidity currents, which have never been recorded to actually exist; as far as I can find.

Fortunately, as Buffy mentions, underwater erosion can be explored experimentally by modestly equipped armatures like ourselves. I’d recommend such table-top experiments, using a range of sediments and water flow rates and patterns. When practical, self-conducted experiments are almost always the most satisfying and reliable sources of experimental data.

THE LATELY TORTURED EARTH: PART V: RIFTS, RAFTS AND BASINS: 23.Canyons and Channels

:hihi: I recommend caution and skepticism concerning the linked-to writing. It’s essentially a Velikovsky-ist work, non-critically citing Velikovsky’s “Worlds in Collision”, a work rejected by nearly all consensus-seeking science and humanities students. If you’ve not already, I recommend you acquaint yourself with the ideas considered either factual or plausible by Velikovskyists, and decide for yourself if you consider them other than severely pseudoscientific. If you find them so, and make this know, you’re likely to be regarded by most scientists and science enthusiasts in about the same esteem as Velikosvsky.

[CharlieO]

CraigD: You have a better grasp of situations than most for sure. Moving BUFFY's, mine and others' comments on submarine canyons to another thread might prove to be both an additional education and a welcomed respite from the daily stress I now must endure. Still learning.

 

I'm still wondering whether these now submarine canyons might actually be evidence of subsurface erosion by Turbidity currents, with seas at or near today's levels, plus or minus on a few hundred meters, OR, more likely, evidence of sea levels once thousands of meters below today's levels and the now submarine canyons being largely evidence of subaerial erosion by rushing river flows across once dry lands; again, possibly due to wide variations in the amount of hydrogen effusions from within Earth.

 

However, please understand I have read works by Velikovsky in the past and I did not quote him directly. I did reference a clearly stated opinion by Landes, which mirrors my own: "What manner of logic allows us to accept evidence, such as marine strata, of a sea-level far above present datum of 25,000 feet, but causes us to run from evidence of a sea-level depression of 25,000 feet?... What is so sacrosanct about current sea level?"

 

I believe Landes' questions remain valid and worth considering. I also believe that largely demeaning Velikovsky appears to be more of an ill advised attempt change the issue of what might be the origin of submarine canyons, without offering any factual evidence in support of Turbidity current erosion. And, I find no relationship between myself and the pseudoscientific writings of Velikovsky, nor do I fear being equated with his illogical ramblings.

 

On the contrary, I would believe my quoted conclusions of a highly qualified marine scientist, Francis P. Shepard, should have been respected and appreciated by any scientifically minded individual. Especially after I made it clear that F. P. Shepard devoted 50 years of his life to studying the origin of submarine canyons, about which he stated clearly and factually:

 

"Investigations of submarine canyons carried on for a number of years with the cooperation of the Coast and Geodetic Survey, the Geological Society of America, Scripps Institution and other organizations have revealed that these sea-floor canyons have all the characteristics of river canyons and are distinctly different from fault valleys. Also tests of the idea that the submarine canyons might be the product of currents have produced negative results so that they have evidently been cut by rivers. The significance of this sub-aerial erosion on the present sea-floor is particularly disturbing, since the submarine canyons extend out to depths of from 2,000 to as much as 10,000 feet and are found off practically every coast of the world."

 

I was also able to find a statement in the Encyclopedia Britannica which supports the same subaerial erosion theory for which F. P. Shepard and many government scientific agencies found substantial evidence.

 

subaerial erosion (geology) -- Britannica Online Encyclopedia

"Submarine canyon formation theories

 

For years the origin of submarine canyons has been the subject of much debate among investigators. Various ideas have been proposed, but prevailing theory favours subaerial erosion as the starting point for a good number of undersea canyons."

 

My opinions, based on long past college courses and my quoting of respected scientific authorities, who have specialized in the research of submarine canyons, is hardly a pseudoscientific effort on my part. However, a table top demonstration of flowing water which ignores the fact that many ocean currents flow at right angles to both exiting river flows and submarine canyons seems to me to be far more pseudoscientific than realistic. For example, from what I have read in the past, the Gulf Stream appears to flow at right angles to the direction of the Hudson River exiting current and across, not down, the Hudson Submarine Canyon, distributing river sediments along Long Island. Plus, the Japanese Current flows at right angles to BUFFY's Salinas River exiting flow in Monterrey Bay and across, not down, the Monterrey submarine canyon.

 

Indeed, some deep ocean currents flow gently upward in their submarine canyons and create an upwelling of nutrients against their continental shelves, which supports their local fishing industries. BUFFY's Monterrey submarine canyon for example, for which he claims instead, "The creation of these canyons occurred during a period when it is known with certainty that they were submerged."

 

Not only do I doubt the creation of these canyons occurred during a period when it is known with certainty that they were submerged, I find no factual evidence of what would have had to be considerable subsurface water erosion by Turbidity currents within these canyons. Plus, "known with certainty" seems a far fetched claim at best, made without any evidence or useful reference, yet I have been frequently demeaned for my claims; which I try to support with factual evidence and sound logic. Still, I can appreciate how a limited knowledge of Earth's marine environment and ocean currents could make one believe a table top demonstration might appear to be a realistic demonstration of subsurface erosion within submarine canyons, if the well known physical facts of the real world were ignored in an attempt to support a widely held assumption.

 

Regards, CharlieO

[Boerseun]

Painted rubber balls might recreate to a certain extent the physical features you might see on Earth. But only superficially.

 

In your rubber-ball example,

- Air was flowing right into the core, from outside the system.

 

If the Earth routinely does what you propose, in other words, shrink and expand,

- where would the extra hydrogen required for an expanding phase, come from?

- before the latest expansionary phase, the Earth must have shrunk, according to your theory. That means that the additional hydrogen required for expansion didn't land on the surface meteorite-style, it was injected right to the core from outside the system.

 

Cracks on the Earth's surface form routinely due to humdrum everyday geological action. Every time there's a slight shake, rattle or roll, the vast majority of them so small that they pass totally unnoticed, things happen to this big ball of rock we're riding on. For instance, slight tremors in Kenia that won't even ruffle your feathers, points to the entire Eastern Africa tearing itself off from the rest of the continent. You say you can't imagine Pangaea tearing itself to pieces, come visit Kenya and see for yourself.

 

Same argument applies to undersea canyons, which are formed in several ways. Crustal movement, subduction, erosion, volcanic activity, rifting, all play a part. But I can guarantee you that with all the diverse causes of canyon-forming, an alternating expanding/contracting Earth has never, and will never feature. And only because it doesn't happen. Expansion needs a helluva lot of externall mass added, and contraction the total opposite, the removal of mass. Earth is not a bubble. Millions of reams of sysmic data says so.

 

Here endeth the lesson.

[CraigD]

In reading about submarine canyons, I found the Hudson River Canyon an interesting one, in part because I’ve sailed over it, so have “been there” feeling, but mostly because its history is well known (it’s a fairly young formation, dating to massive glacial draining period about 10,000 years ago that created Long Island and madeover pretty much the entire New England coast), and its present form contains sections known to have once been above sea level, sections known to have always been below, and three different “headwaters” due to the shift in the mouth of the Hudson from Newark Bay to Raritan Bay to, about 6,000 YA, its present location in New York Bay.

 

These many features are pretty compelling evidence that undersea canyons can either form completely underwater, or form above and later be flooded. As Boerseun notes, there are several other mechanisms by which they can form.

 

All this strongly suggests to me that, though tempting in its simplicity, it’s a mistake to conclude that similar-looking formations must have been created by similar events, or even that a single formation was created by a single kind of event.

[CharlieO]

BOERSEUN: Admittedly I have problems with a very slow dial-up and poor connection, which makes searching for claims you made about my posts very time consuming. Re: "You say you can't imagine Pangaea tearing itself to pieces."

 

Couldn't find that statement you attributed to me anywhere. Perhaps you could locate it for me if you did for yourself?

 

While not the issue of this thread, what I did write was, "Clearly, to me at least, ALL the continents were once much larger in size and were also connected together, everywhere, on a not too much smaller Earth. This made more sense to me than a Pangaea located as a lump of crust on only one side of Earth."

 

Still seems logical to me and, I must add, to many others who dare to wonder and speculate as to possible alternatives. I even provided a possible mechanism for Earth's expansion in an earlier post: Hydrogen molecules emerging from a dense, highly compacted, metallic hydrogen core, changing phase and effusing into Earth's mantle, thereby expanding between other crystals and increasing overall size as hydrogen embrittlement still does today in industry, while still retaining the same total mass and density. This is a process which I have personally initiated under laboratory conditions and one possible explanation for those who are not so devoted to one dogma that they can consider other alternatives.

 

Not exactly sure what you meant by, "But I can guarantee you that with all the diverse causes of canyon-forming, an alternating expanding/contracting Earth has never, and will never feature. And only because it doesn't happen." Sounds pretty absolute to me and I guess you are saying an alternating expanding/contracting Earth has never and will never happen. Is that correct? If so, I wish I could be so certain about dogmatic beliefs. But then, not too long ago, most scientists were claiming Earth was flat, while others also claimed the Sun rotated around Earth. In 1928, Will Rogers wrote: "So much of what we KNOW, ain't true." Amen.

 

While again not the issue, I must explain my creed as an explanation for my efforts, "I cannot conceive of anyone surviving their physical death, yet I can respect and sympathize with others believing they might be rewarded in their afterlife. I only want to know more about life's present mysteries and will strive to comprehend a portion, be it ever so tiny, of the Reason manifesting itself in Nature. When I die, that others found my efforts worthwhile is the only reward I seek."

 

As for the issue of this thread, you seem to be saying undersea canyons are formed in several ways: "Crustal movement, subduction, erosion, volcanic activity, rifting, all play a part" - - with no mention of subaerial erosion by river flows across once dry lands.

 

Have you ever considered the grandeur of these submarine canyons, some of which are deeper, longer and wider, with a larger displacement than the Grand Canyon by many factors? Did you also fail to consider the fact that oceans have coastal currents, most of which flow at right angles to exiting subaerial river flows and their submarine canyons? Ocean currents can only distribute river sediments along their coasts and river deltas, they can't erode submarine canyons. Hardly any support for Turbidity currents and their debris, which many still claim to have eroded most submarine canyons. Also please consider, many submarine canyons have rising water currents, called upwelling, which carry deep sea nutrients to their coasts and supports local fishing industries.

 

One feature of submarine canyons you might also consider is the existence of Plunge Pools beneath escarpments located across these submarine river courses. Plunge Pools are eroded depressions resulting from water falling freely from above. These are also evident on land, such as those currently found beneath Niagara Falls, Yellowstone Falls and ALL others; albeit many submarine canyon plunge pools are larger overall and thus evidence of much greater water flows falling freely from escarpments high above; which would be illogical, if not impossible for underwater currents. Can you tell me how an upwelling submarine canyon current could dig out a plunge pool while flowing straight up a now submerged escarpment?

 

You might also consider the sand from continental sources, now deposited in obvious layers along submarine river banks, just as they are found today along subaerial rivers, with clearly evident wind blown ripples and sand dunes on their surfaces, now stabilized underwater. Then consider the cobbles or rounded river rocks, again of continental sources, which can be found in these former river beds, now hundreds of miles from shorelines. I doubt if any of this could develop underwater thru crustal movement, subduction, volcanic activity or rifting, or even Turbidity currents.

 

The latter appears to be both difficult to locate and, when some underwater currents were found, they appeared to be too weak to create such dramatic effects or even leave evidence of their passing.

 

Now I am aware that some claim the ocean floors must have risen tens of thousands of feet above existing sea levels by Tectonic means, so the evident subaerial erosion could occur, while sea levels remained within a limited range of several hundreds of feet. If so, then all the sea floors rose at the same time and this would require a suddenly expanded Earth and then a slowly condensing Earth, so there goes your absolute "never, and will never" contention. So I think we can agree to ignore this claim as being illogical.

 

So what is it about an expanding Earth or a dried out Earth, or both, that creates such resistance to even the consideration of possible alternatives? Could it be your education has robbed you of any imagination or the ability to deviate from current dogma? Noting that dogma often changes slowly over time. Flat Earth, remember? In any event, I can sympathize with those both lacking imagination and unable to even consider possible alternatives, just as I can sympathize with like-minded Creationists.

 

However, if you can clearly disprove the underwater evidence of subaerial erosion by rivers flowing across once dry continental shelves and margins, onto ocean floors, please inform the many researchers who have devoted their professional lives to this study: Shepard, Gross, Landes to name a few. You might also want to contact the Editors of the Encyclopedia Britannica, the Coast and Geodetic Survey, the Geological Society of America, Scripps Institution and many other marine research organizations all over the world, which have concluded these sea-floor canyons have all the characteristics of river canyons and are distinctly different from fault valleys.

 

Shepard writes: "Also tests of the idea that the submarine canyons might be the product of currents have produced negative results so that they have evidently been cut by rivers. The significance of this sub-aerial erosion on the present sea-floor is particularly disturbing, since the submarine canyons extend out to depths of from 2,000 to as much as 10,000 feet and are found off practically every coast of the world."

 

I'm sure he would appreciate learning the error of his conclusions, if you were able to disprove the physical facts he observed over his 50 years of marine research.

 

Meanwhile, I can agree, as CraigD hopefully offered, the subaerial erosion of now submarine canons is a simplistic explanation, but the physical evidence seems clear. I believe it was Einstein who said the simplest explanations are usually the most correct. E=MC^2.

 

Regards, CharlieO