Drumlins, Ribbed Moraines, and Giant Ripples

[otseng]

This thread is an offshoot of the Channeled Scablands thread.

In that thread, I asked "If a catastrophic flood created the Scablands in a short period of time, couldn't other geological features elsewhere be also created in a short amount of time?"

One of the features in the Scablands are the giant ripple marks.


http://www.detectingdesign.com/harlenbretz.html

Similar to giant ripple marks are drumlins and ribbed moraines.

Question for debate:
How did all these giant ripples form?

[otseng]

When a glacier advances, it acts like a bulldozer, however, because there is a lot of pressure on the bottom of the glacier, the bottom of the glacier is very fluid.

It gouges out the lakes when it push dirt out of the way below a later water table.

Some questions.

How can a glacier go downward into the ground? If it could go downward, how can ice carve rock? It's hard enough for metal to carve rock, how can ice do it? And where did it push the carved out rocks to? If this is true, should we not also see glacier scraping all along the bottom of the lakes?

There ARE lakes that have drumlins within them you know.. they are not mutually exclusive.

And it's easily explainable by receding water.

[Goat]

When a glacier advances, it acts like a bulldozer, however, because there is a lot of pressure on the bottom of the glacier, the bottom of the glacier is very fluid.

It gouges out the lakes when it push dirt out of the way below a later water table.

Some questions.

How can a glacier go downward into the ground? If it could go downward, how can ice carve rock? It's hard enough for metal to carve rock, how can ice do it? And where did it push the carved out rocks to? If this is true, should we not also see glacier scraping all along the bottom of the lakes?

There ARE lakes that have drumlins within them you know.. they are not mutually exclusive.

And it's easily explainable by receding water.

there is the weight of tons upon tons of ice pressing down on the ground, with rocks and boulders also on the bottom, and you have to ask this?

[Jose]

A great discussion. My apologies for being too busy to take part recently. I'll add a bit or two from what I know (or think I know).

Do drumlins and ribbed moraines occur anywhere where there hasn't been glaciation?

This is difficult to answer because the deck is stacked.

By definition, moraines are "rock debris, fallen or plucked from a mountain and transported by glaciers or ice sheets." (Wikipedia) And drumlins are "elongated whale-shaped hill formed by glacial action." (Wikipedia)

And how do we know where there has been glaciation? By the presence of such things as moraines and drumlins.

So, if I point to a drumlin, by definition, it'll automatically be considered a glacier area.

Your point is well taken. By the current definitions, the reasoning seems circular. Let's ask what information is behind the definitions.

First, where do we find drumlins and moraines? In the northern hemisphere, they tend to be to the south of areas that "look different" from what is to the north. South of a certain point, we find no more moraines. So, we ask: what is different about the northern and southern regions of these formations?

Well...in the hills of southern Indiana, we find horizontal strata, mostly interleaved limestone and shale, with some beds of sandstone. These are slightly uplifted into the "Interior Low Plateaus," so that erosion has formed some very attractive ravines. As you drive north, you eventually come to what I call The Last Hill between southern Indiana and Banff.

It's one of a line of hills just south of Indianapolis, some of which are being mined for gravel. These hills are not stratified; they are piles of miscellaneous rock debris. To their north is smooth land, mostly farms now, previously mostly "flatwoods." Farther north, around the Lakes, are the drumlins. North of them (and west, in Wisconsin and Minnesota) is the Land of Lakes--bazillions of "kettle holes."

We can add to this a bit of botany. On the northern slopes of some of the steeper and deeper ravines we can find hemlocks that normally don't grow this far south. There are little pockets here and there of ecosystems that typically require colder regions. How did they get here?

There are two more things to add: First, scrape marks--parallel grooves in rocks north of the piles of rock debris. My favorites aren't in Indiana, but in New Hampshire at the summit of Mt. Kearsarge. They come up the mountain from the north-northeast, over the top, and down the other side. Such things were noticed long ago:

These grooves, and other signs of ice action, give the clearest evidence that, during the Glacial Peiod, the White Mountains were covered by a centralmer-de-glace, which discharged local glaciers into the principal valleys radiating from the central peaks.
Ice-Marks and Ancient Glaciers in the White Mountains
A. S. Packard, Jr.
American Naturalist, Vol. 1, No. 5 (Jul., 1867), pp. 260-269

The second interesting thing is the occasional large boulder composed of rock that is wholly unlike the rock in the surrounding area. One finds these large boulders sitting around here and there...but only to the north of the piles of rock debris. They tend to be rock types similar to those of exposures far to the north. Something carried them south, then set them down on the surface--but never farther south than the piles of debris.

So...here's a bunch of observations. How do we explain them? Here are some thoughts:

• The northern trees that are too far south: Perhaps the climate was cooler long ago, and the northern forests spread farther south than they do now. Upon warming up, these types of trees died out where they were not protected by local microclimates. Here's a suggestion that the weather was cooler once.
• To the north of the debris piles it's relatively smooth; to the south, the terrain is highly convoluted: Perhaps there was some kind of giant bulldozer that pushed south, breaking up rock as it went, eventually leaving a debris pile at the southern limit of its path. The cold weather south of the debris pile suggests that this bulldozer did its work in the cold.
• The odd boulder here and there: Perhaps the giant bulldozer dropped an occasional boulder. It's hard to see how a huge, wide bulldozer could drop something; maybe we need to consider the idea that the bulldozer went away and left its load of rocks and boulders where they were. If the bulldozer were a glacier, then melting would explain this. If the bulldozer were liquid water, it's hard to see how the fine particles would sediment out before the large rocks; usually, the rocks sink faster. The bulldozer seems more likely to have been frozen.
• The parallel grooves: Perhaps the giant bulldozer had a fairly rough scraping surface. If the bulldozer were a glacier, the scrapers would be rocks on the bottom of the glacier. If there are a bunch of such rocks, then the grooves they'd leave behind would be parallel.
• The debris pile: bulldozers push debris before them into piles. Current glaciers also do, leaving terminal moraines at their ends. The debris pile, coupled with the cold weather and the scrape marks, combined with the fact that the bulldozing is to the (colder) north of the debris and not to the (warmer) south, argues that the debris piles are moraines and the bulldozers were glaciers.
• The Lakes. This is a little harder to visualize, and requires more data to become compelling, but the geologists' explanation is this: those glaciers were heavy. Just as sitting on the edge of a rowboat tends to make the boat tilt to the heavy side, so piling a lot of weight on top of North America deformed the rock downward. The Great Lakes, as I understand it, are the remnants of Lake Agassiz, which filled in this depression. The smaller lakes--the kettle holes--are explained as smaller depressions left by chunks of glaciers in the years (millennia?) during which they were no longer advancing, and before they finally melted away.

What about the drumlins? I have a vague notion that I've read that they are thought to be moraines that were over-run by later glaciers, but not entirely scraped away. I could be wrong about that...but it fits with their tendency to be in fields, and in parallel orientations. If those in one place are oriented north/south, and those in another place are oriented east/west, that rather suggests that the direction of flow of those two parts of the glacier were somewhat different.

Does it make more sense to suggest that they were formed by water, rather than by ice? I don’t know. But, all of the other evidence points to glaciers. The "glacial erratics"--those giant boulders that are out of place--argue that the most recent event was glacial, and not a flood. If it had been a flood, then the boulders would be under sediment that settled out after the boulders had hit the bottom.

So...back to the definitions. The definitions are written in the light of the combined data that lead geologists to infer what these things are. The definitions did not exist first, with geologists then coming along and saying "looky here--one of those whale-shaped hills that is said to be formed by glaciers! Let's say there was a glacier here once." Rather, they said, "odd--a bunch of whale-shaped hills that are aligned in the same direction. What the hey? What else can we find out that could lead us to an explanation?" Their explanation is then written down as the definition of the term they invent to refer to that particular type of formation.

It occurs to me that, if a drumlin is defined as a glacially-formed hill of a certain type, then a hill of the same shape that was formed differently is not a drumlin. You'd say, "huh...this looks like a drumlin, but it's in the wrong context for a glacial feature. Let's figure this out."

Or, are you just speculating. I don't have a geology degree. DO you?

Whether I have a geology degree or not is immaterial.

All I ask is an explanation of the mechanism of how a glacier is able to carve out a lake and also leave drumlins.

I agree with otseng, here, goat. The challenge here is to develop our own understanding of things; a part of that is to ask "yeah, but what if..." Non-scientists may ask what-ifs that seem pretty nonsensical to scientists, just as I ask what-ifs of historians or philosophers that seem pretty stupid to them. Personally, I rather enjoy the what-ifs (especially yours, otseng) when they are calmly and respectfully phrased. They challenge me to evaluate where my "knowledge" is based on hard data and reasonable logic, and where it's based on assumptions that may be less than solid. My colleagues and I ask each other nasty questions all the time, but they're never at the level of the Basic Assumptions of the field--because we share the same assumptions. I tend to get challenges at that level only on these forums.

How can a glacier go downward into the ground? If it could go downward, how can ice carve rock? It's hard enough for metal to carve rock, how can ice do it? And where did it push the carved out rocks to? If this is true, should we not also see glacier scraping all along the bottom of the lakes?

As noted above, I think the idea is deformation of the crust, forming the depressions in which the lakes lie. So, the glaciers (we think) didn't carve out the lake basins and push the debris to Indianapolis. Nor did they carve out the lake basins and push the debris into some big drain at the bottom. It's easier to think of the lake basins as the footprint of a giant ice monster that stood there for a very long time.

---

In any event, the main point is that we need to look at a whole body of evidence to come up with our explanations. To say "I could explain XXX by YYY" doesn't help if YYY contradicts some other set of observations, and is therefore ruled out. I have a sense that a lot of the debate in discussions like these stems from looking at single observations and trying to explain them differently. We need to look at multiple observations, so that we have plenty of reality-checks for our explanations.

[otseng]

Just want to say welcome back Jose. I've always considered you one of my strongest debaters to contend with. And I look forward to this discussion with you.

[otseng]

A little trivia intermission.

Louise Agassiz was the first scientist to propose the ice age theory.

In 1837 Agassiz was the first to scientifically propose that the Earth had been subject to a past ice age.

http://en.wikipedia.org/wiki/Jean_Louis ... an_ice_age

But interestingly, he "saw the Divine Plan of God everywhere in nature, and could not reconcile himself to a theory that did not invoke design. "

The combination in time and space of all these thoughtful conceptions exhibits not only thought, it shows also premeditation, power, wisdom, greatness, prescience, omniscience, providence. In one word, all these facts in their natural connection proclaim aloud the One God, whom man may know, adore, and love; and Natural History must in good time become the analysis of the thoughts of the Creator of the Universe. . .

http://www.ucmp.berkeley.edu/history/agassiz.html

[otseng]

South of a certain point, we find no more moraines.

I've been trying to find what that point would be. Can anybody show how far the glaciers advanced?

The second interesting thing is the occasional large boulder composed of rock that is wholly unlike the rock in the surrounding area.

I've created a separate thread to discuss this more in detail - Glacial Erratics.

I think the idea is deformation of the crust, forming the depressions in which the lakes lie.

Can anybody provide a link explaining how glaciers can carve/form lakes? (Maybe this should be a separate thread too)

[Jose]

South of a certain point, we find no more moraines.

I've been trying to find what that point would be. Can anybody show how far the glaciers advanced?

Well, drawing a line north/south through Indianapolis, we'd say that those particular glaciers made it just past Indy. This map shows that this particular set of moraines have been named the Wisconsonian glaciation, dated to 10-30,000 years ago. The dark line labeled as Wisconsonian is marked, if that's the word, by piles of un-stratified rock and debris.

The next dark line farther south marks the Illinoisan glaciation's set of terminal moraines. This was an older glaciation, around 200,000 years ago. Bloomington is south of this, on what is called "the Mitchell Plain"--a higher part of the "plateau" with more ravines and gullies and the like than we find around Martinsville. Martinsville is about half-way between Bloomington and Indy, and is in a valley surrounded by rather smoother hills than around Bloomington and in Brown County.

I've never looked for the Illinoisan moraines, so I can't say much about them. but, from the "obvious" appearance of the Wisconsonian moraines, I'd bet that there are the tell-tale signs.

So, the short answer is: if you find a line of moraines (rubble piles) where you can't find an obvious way to create them, you're probably looking at the southern limit of glaciation. (You'd want more observations than this, to be sure you're not looking at the place they dumped the dirt when the bulldozed the WalMart parking lot, but this is the general idea.)

The second interesting thing is the occasional large boulder composed of rock that is wholly unlike the rock in the surrounding area.

I've created a separate thread to discuss this more in detail - Glacial Erratics. Good idea, though the discussion might be a bit erratic.

I think the idea is deformation of the crust, forming the depressions in which the lakes lie.

Can anybody provide a link explaining how glaciers can carve/form lakes? (Maybe this should be a separate thread too)[/quote]I've noodled around a bit, but haven't found a suitable link. There's the occasional USGS treatise of a bazillion pages, and there's the occasional State Park "this is what happened" summary, but it's hard to find something in-between. We'll need to keep looking.

[otseng]

I've created a separate thread to discuss this more in detail - Glacial Erratics.

Good idea, though the discussion might be a bit erratic.

That's fine that it's erratic. As long as we leave no stone unturned.

[Goat]

I've created a separate thread to discuss this more in detail - Glacial Erratics.

Good idea, though the discussion might be a bit erratic.

That's fine that it's erratic. As long as we leave no stone unturned.

Most of the erratic stones were turned already by the glaciers, according to the geologists.

[otseng]

As I've demonstrated, water action is the best explanation of drumlins, ribbed moraines and ripples. We see such things all the time on a small scale at beaches and rivers.

As for ice action, there are no adequate explanations of these formations.

Drumlins are streamlined ice-moulded glacial bedforms which are generally elliptical in plan view. Despite over thirty years of intensive study, the exact conditions and processes responsible for their formation remain undetermined.

http://voa.soc.soton.ac.uk/soes/researc ... mlins.php3

It's proposed that glaciers melting can leave these formations. Yet, this is conjecture since there are no evidence that glaciers now have produced drumlins or ribbed moraines. And there is not even a mechanism proposed on how this can occur.

And we even have drumlins that are more than 150 ft high. How can that be formed by a retreating glacier?

Drumlins, which may be more than 150 ft (45 m) high and more than 1/2 mi (.8 km) long, are common in New York, Wisconsin, Canada, and Northern Ireland.

http://www.encyclopedia.com/doc/1E1-drumlin.html

So, water action is the most logical explanation. Yet, why do geologists still claim that they are formed by ice?

There is only one reason. It would lend credence to the Biblical flood and that is unacceptable to naturalistic scientists.

Geologists customarily explain drumlins as debris piled up and sculpted by the ice sheets themselves, despite the fact they look like they might have been shaped by flowing water. As we all know, the word "flood" is an anathema in geology, probably because a provable episode of extensive flooding would lend credence to the Biblical Flood!

http://www.science-frontiers.com/sf066/sf066g11.htm

So, rather than dismiss a hypothesis based on its implications, geologists should simply choose which is the better hypothesis based on evidence and the most plausible explanation.