Glaciers, Part Two: Ice Age Floods, or: My God is an awesome God.
A few days ago I mentioned attending a
presentation on glaciers, and how any discussion
of glaciers must necessarily mention that
glaciers worldwide are rapidly disappearing due to
global warming. There's another related topic
that usually comes up in any discussion of
glaciers: the Ice Age Floods.
There are a number of geological features of
eastern Washington State whose formation is an
amazing story. About 65 miles from where I live
is an enormous waterfall. It's three and a half
miles wide, and four hundred feet high, making
Niagara Falls look like a mere trickle in
comparison. Why haven't you ever heard of this
waterfall? Because Dry Falls is just that: a dry
waterfall; having been dry since the end of the
last Ice Age.
Throughout Eastern Washington, in the area known
as the Channeled Scablands, you'll find coulees
and canyons carved hundreds of feet deep into the
basalt formations. One would guess that they were
cut by running water, but there's no water there
now. What happened? And the landscape is
littered with rocks that are clearly out of place
among all this basalt. How did they get there?
A geologist named J. Harlen Bretz found the
answers to these questions, and revealed them in a
series of papers he published starting in 1923.
During the last Ice Age, a lobe of the Cordilleran
ice sheet blocked the Clark Fork River near the
border of what is now the northern panhandle of
Idaho and the state of Montana, forming Glacial
Lake Missoula. At its maximum, Lake Missoula was
2000 feet deep, and contained over 500 cubic miles
of water – more than Lake Erie and Lake Ontario
combined. At the site of today's city of
Missoula, Montana, the water would have been
nearly 1000 feet deep. From time to time,
however, the water worked its way through the ice
dam, breaking free and spilling the contents of
Lake Missoula over a period of perhaps less than
two days. The leading edge of the ensuing flood
was over 200 feet high, perhaps nearly 10 times
that height, and tore through the landscape at 60
miles per hour. As this flood poured through
eastern Washington, it carved the coulees of the
Channeled Scablands and the great Dry Falls. And
the out-of-place rocks you'll find scattered
throughout eastern Washington, known as
“erratics”, were carried to their current resting
places in the flood in chunks of ice. Some of
these erratics are as big as a house.
This enormous flood didn't just happen once,
though. After the ice dam broke and Lake Missoula
was drained, the glacier once again found its way
into the path of the Clark Fork River, reforming
Glacial Lake Missoula and starting the whole
process over again. It has been determined that
the lake formed, broke through the ice dam, and
flooded eastern Washington at least 40 times,
possibly as many as 100 times.
So how do we know all this stuff? Besides the
obvious, like the Channeled Scablands and Dry
Falls, there's much more. In the area where
Glacial Lake Missoula formed, you can see the
giant “ripples” left as the water flowed out. And
you can see the high-water marks of the lake,
hundreds of feet above the valley floor. Analysis
of the minerals in the “erratics” rocks have
determined where some of them came from, many
miles away. But what I think is one of the
coolest pieces of evidence is the sediment layers
geologists have found. In several places in the
northwest, there are sediment layers that are much
thicker than the normally very thin layers
deposited by annual runoff, and contain much
coarser materials. These are the sediments left
behind by the great floods. Between the
flood-deposited layers, however, are the much
thinner layers left by annual runoff. By counting
the annual runoff layers between the flood layers,
geologists can determine how many years passed
between successive floods. And so we know that
these massive floods occurred every 50 years or so
on average, and continued for at least 2000 years.
By now, you're probably wondering why the
alternative title, “My God is an awesome God”?
I am not a Creationist, or a “young earth”
believer. I do believe that God created the
Earth, the Universe, and everything in it, but I
also believe the scientific explanations of how He
did it. I have no problem with this and I see no
contradictions in this belief. God created it,
science tells us how He did it.
To me, the notion that God simply waved His hand
on the third day and created the land, complete
with the Channeled Scablands, Dry Falls, and all
the other evidence of the Ice Age Floods, suggests
a God with limited imagination. But to cause an
Ice Age, to have a glacier block off a river and
make an enormous lake, to have the ice dam break
and turn loose a massive wall of water, hundreds
of feet high, that roared across the state of
Washington, and then to repeat this again and
again, 40 or more times over a period of several
thousand years, now there's a God with real
imagination! My God is not only the Creator, he's
an engineer, he's an artist. He dreams up
incredible ways of forming the landscape, then He
takes his time, carrying out His plans over a
period of thousands of years. What's more, He
leaves behind traces of His handiwork, little
clues that allow us to solve the mysteries of His
creation. My God is an AWESOME God, and science
shows us just how awesome He is!
presentation on glaciers, and how any discussion
of glaciers must necessarily mention that
glaciers worldwide are rapidly disappearing due to
global warming. There's another related topic
that usually comes up in any discussion of
glaciers: the Ice Age Floods.
There are a number of geological features of
eastern Washington State whose formation is an
amazing story. About 65 miles from where I live
is an enormous waterfall. It's three and a half
miles wide, and four hundred feet high, making
Niagara Falls look like a mere trickle in
comparison. Why haven't you ever heard of this
waterfall? Because Dry Falls is just that: a dry
waterfall; having been dry since the end of the
last Ice Age.
Throughout Eastern Washington, in the area known
as the Channeled Scablands, you'll find coulees
and canyons carved hundreds of feet deep into the
basalt formations. One would guess that they were
cut by running water, but there's no water there
now. What happened? And the landscape is
littered with rocks that are clearly out of place
among all this basalt. How did they get there?
A geologist named J. Harlen Bretz found the
answers to these questions, and revealed them in a
series of papers he published starting in 1923.
During the last Ice Age, a lobe of the Cordilleran
ice sheet blocked the Clark Fork River near the
border of what is now the northern panhandle of
Idaho and the state of Montana, forming Glacial
Lake Missoula. At its maximum, Lake Missoula was
2000 feet deep, and contained over 500 cubic miles
of water – more than Lake Erie and Lake Ontario
combined. At the site of today's city of
Missoula, Montana, the water would have been
nearly 1000 feet deep. From time to time,
however, the water worked its way through the ice
dam, breaking free and spilling the contents of
Lake Missoula over a period of perhaps less than
two days. The leading edge of the ensuing flood
was over 200 feet high, perhaps nearly 10 times
that height, and tore through the landscape at 60
miles per hour. As this flood poured through
eastern Washington, it carved the coulees of the
Channeled Scablands and the great Dry Falls. And
the out-of-place rocks you'll find scattered
throughout eastern Washington, known as
“erratics”, were carried to their current resting
places in the flood in chunks of ice. Some of
these erratics are as big as a house.
This enormous flood didn't just happen once,
though. After the ice dam broke and Lake Missoula
was drained, the glacier once again found its way
into the path of the Clark Fork River, reforming
Glacial Lake Missoula and starting the whole
process over again. It has been determined that
the lake formed, broke through the ice dam, and
flooded eastern Washington at least 40 times,
possibly as many as 100 times.
So how do we know all this stuff? Besides the
obvious, like the Channeled Scablands and Dry
Falls, there's much more. In the area where
Glacial Lake Missoula formed, you can see the
giant “ripples” left as the water flowed out. And
you can see the high-water marks of the lake,
hundreds of feet above the valley floor. Analysis
of the minerals in the “erratics” rocks have
determined where some of them came from, many
miles away. But what I think is one of the
coolest pieces of evidence is the sediment layers
geologists have found. In several places in the
northwest, there are sediment layers that are much
thicker than the normally very thin layers
deposited by annual runoff, and contain much
coarser materials. These are the sediments left
behind by the great floods. Between the
flood-deposited layers, however, are the much
thinner layers left by annual runoff. By counting
the annual runoff layers between the flood layers,
geologists can determine how many years passed
between successive floods. And so we know that
these massive floods occurred every 50 years or so
on average, and continued for at least 2000 years.
By now, you're probably wondering why the
alternative title, “My God is an awesome God”?
I am not a Creationist, or a “young earth”
believer. I do believe that God created the
Earth, the Universe, and everything in it, but I
also believe the scientific explanations of how He
did it. I have no problem with this and I see no
contradictions in this belief. God created it,
science tells us how He did it.
To me, the notion that God simply waved His hand
on the third day and created the land, complete
with the Channeled Scablands, Dry Falls, and all
the other evidence of the Ice Age Floods, suggests
a God with limited imagination. But to cause an
Ice Age, to have a glacier block off a river and
make an enormous lake, to have the ice dam break
and turn loose a massive wall of water, hundreds
of feet high, that roared across the state of
Washington, and then to repeat this again and
again, 40 or more times over a period of several
thousand years, now there's a God with real
imagination! My God is not only the Creator, he's
an engineer, he's an artist. He dreams up
incredible ways of forming the landscape, then He
takes his time, carrying out His plans over a
period of thousands of years. What's more, He
leaves behind traces of His handiwork, little
clues that allow us to solve the mysteries of His
creation. My God is an AWESOME God, and science
shows us just how awesome He is!
posted by Jim Allyn at 4/17/2006 09:27:00 PM
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