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Geology and Geologic Time through Photographs

Archive for the category “climate change”

“Crazy Modern Period” -a vanishingly thin sliver of Earth History

I’m in Florida, visiting my mother. There’s a beach, waves, shorebirds… And it’s warm! Late last week, my youngest daughter and I boarded a plane in Portland, Oregon, flew to Chicago –and then on to Fort Myers, Florida –across the continent for a distance of nearly 3000 miles. Being the holidays, the airports were packed, with people going in all directions, all over the planet. And like most people, we arrived at our destination the same day we departed.

Above the clouds --somewhere over eastern Oregon.

Above the clouds –somewhere over eastern Oregon.

Of course, just about everybody agrees that us human-types do pretty amazing things, like fly across the continent in a day and communicate instantly with family, friends, and colleagues on the other side of the planet. Oh for goodness sake… human beings have traveled to the moon and sent spacecraft to Mars!

In the context of geologic time, however, humanity and its accomplishments are positively mind-boggling. Homo sapiens dates back some 100,000 years, a miniscule period of time given that Earth is 4.55 billion years old. But it wasn’t until 1933, less than 100 years ago, that humans entered the “crazy-modern period” –when we flew the first airline flight across the US with no overnight stops. At that point, all parts of our planet became readily accessible to the public.

Divide 100 years by 4.55 billion? Our “crazy-modern period” is one 45.5 millionth of Earth history. What a unique moment in Earth history we’ve created! No other species has come close to anything like this –ever— in 4.55 billion years.

Sanibel Island and the Florida Gulf Coast --while descending into Fort Myers

Sanibel Island and the Florida Gulf Coast –while descending into Fort Myers

I won’t try to speculate how long our resources and (relatively) clean environment will last, but if we don’t figure out a way to live sustainably, these amazing times will soon disappear no matter how smart we are. Our sliver of Earth history will remain vanishingly small. Earth will heal, of course –but humans don’t have the same luxury of geologic time.

Regardless of whether or not we survive our successes, all of us share this unprecedented time. Here’s to another solstice passing –and to another calendar year. _MG_3784

Lakes drying up in southeastern Oregon –geologically, very quickly

Lake Abert’s one of the coolest lakes in Oregon –in my opinion.  It’s got birds along its shoreline because it hosts a huge population of brine shrimp (which smell, by the way).  It has the brine shrimp because it doesn’t have any fish –and it doesn’t have fish because it’s an alkali lake in a closed basin, full of salt. The water that goes into this lake stays there, until it evaporates.  When it evaporates, it leaves behind more salt.

Birds along small creek that empties into Lake Abert, Oregon.

Birds along small creek that empties into Lake Abert, Oregon.

Over the past few years, the lake seems to be drying up faster than usual–which makes all the sense in the world because we’ve had less rainfall than usual over the past few years.  There’s still water, but it’s noticeably farther out into the “lake” than before.  That’s certainly fast.  We, as humans, can watch this lake dry up over just a few years.

salt deposits at Lake Abert, Oregon

salt deposits at Lake Abert, Oregon, looking northward.  Abert Rim, along the right side of the photo, is uplifted along a normal fault.

But think of what the lake was 20,000 years ago, at the height of the last glaciation!  The physiographic map below shows Lake Abert (along US 395) as part of the much larger Lake Chewaucan, which included the even larger Summer Lake basin to the west.  There’s all sorts of evidence for this earlier lake: old shorelines, deposits at elevations well above the modern lake, gravel bars.  And Lake Chewaucan was only one of many such Pleistocene, or “pluvial” lakes that occupied closed basins in the Oregon and Nevada Basin and Range.

Distribution of Pleistocene lakes in the southern Oregon Basin and Range.

Distribution of Pleistocene lakes in the southern Oregon Basin and Range.

Of course these ages do a “time-number” on me.  20,000 years is a short time, geologically.  So just yesterday, this region had many of these large large lakes –and in just a short time, they’ve dwindled to isolated remnants.  But in just the last 5 years, those remnants have dwindled even more.  It’s dramatic.  It’s frightening.

Odd too –those Young Earth Creation types think that planet Earth is younger than Lake Chewaucan!  And really?  Lake Chewaucan couldn’t have formed unless there was a basin there –and do you see the cliffs on the right (east) side of the lake?  That’s Abert Rim, uplifted by a big normal fault –which is what formed the basin.  So, the 2000′ of  uplift on this fault must be older than the lake, which is older than planet Earth!  Cool!


For more photos of Lake Abert, type “Lake Abert” into the geology search engine.
For information about the completely new (available in November, 2014) Roadside Geology of Oregon book.

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