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Posts Tagged ‘Antelope Oregon’

Shaniko and the Clarno Unit, Oregon

Posted by graywacke on September 12, 2013

First timer?  In this formerly once-a-day blog (and now more-or-less a twice a week blog), I have my computer select a random latitude and longitude that puts me somewhere in the continental United States (the lower 48).  I call this “landing.”  I keep track of the watersheds I land in, as well as the town I land near.  I do some internet research to hopefully find something of interest about my landing location.  To find out more about A Landing A Day (like who “Dan” is and what the various numbers and abbreviations mean in the first paragraph), please see “About Landing,” (and “Abbreviations” and “Cryptic Numbers”) above.

 Landing number 2051; A Landing A Day blog post number 469.

Dan –  The misery continues (1/9) with this OSer landing in . . . OR; 78/66; 2/10; 8; 152.8.  I mean, really – the odds are about 49/51 USer/OSer.  Just because I always root for USers, does the LG (“landing god”) have to frown down upon me?

Here’s my regional landing map:

landing 1

My closer-in landing map shows that I landed closest to Shaniko, but not far from Antelope and the “John Day Fossil Beds” National Monument:

landing 2

My Google Earth (GE) shot is looking south, up a valley:

ge 1

The valley in which I landed is home to an unnamed tributary, which flows to the Pine Hollow Ck (the valley to the far left), which flows to the John Day River (8th hit).  The John Day heads more or less straight north about 50 miles where it discharges into the Columbia (145th hit).

So what about Shaniko?  From Ghosttowns.com:

The town of Shaniko was no accident. It was planned (around 1900) before it was born. It was the brainchild of a group of bankers and businessmen in The Dalles (a town on the Columbia River about 50 miles north of  Shaniko).  The reason for the town was the enormous production of wool, Central Oregon being one huge sheep ranch in the 1900s.

The only outlet for these thousands of bales of fleece was the The Dalles.  In 1898, in order to expedite the shipment of wool, a railroad was brought in from Biggs Junction on the Columbia River, just upstream from the Dalles.  Since a railroad could not be useful without a terminal, Shaniko was built for that express purpose.

And, from Wiki:

One of the earliest settlers (before the railroad) was August Scherneckau, who came to the area after the Civil War,  in 1874.  The spelling of the town’s name reflects local pronunciation of Scherneckau’s name.

That’ll do it for Shaniko.  I’ll move right along to the John Day Fossil Beds National Monument.  It turns out that there are three separate parks (termed “units”) that make up the National Monument.  The one closest to my landing is the Clarno Unit.

As a a duly interested geologist, I went to the webpage for the National Monument, and began reading about the Clarno Unit.  I was appalled.  Here’s my personally-guided tour of the verbiage on their website.  Everything you read in black is theirs; my comments (obviously) are in blue.

The Clarno Unit is located 18 miles west of the town of Fossil.  The Palisades are the most prominent landform.  44 million years ago a series of volcanic mudflows, swept up and preserved a diverse assortment of plants and animals that inhabited a near-tropical forest.

OK, so the writing style is choppy, one may not know what the Palisades are, there’s an unnecessary comma, and how about “engulfed” instead of “swept up?”  Here’s their picture of the Palisades:

palisades from nps

Tiny four-toed horses, huge rhino-like brontotheres, crocodilians, and meat-eating creodonts that once roamed ancient jungles are now found in the rocks of the Clarno Unit, as well as an incredibly diverse range of plant life. Leaves, fruits, nuts, seeds, and petrified wood from 173 species of trees, vines, shrubs, and other plants have been found here thus far.

OK.  No significant problems (although the word “fossil” has yet to appear).  This is all that the home page says.  But wait, there’s a link to learn more about the geology . . .

The Clarno Nut Beds formed when massive mudflows engulfed a forest.

Clarno Nut Beds?  What are they talking about here?  Sure, there were some nuts on some trees in the forest, but there’s a whole bed of nuts?

The Clarno strata consist of thick layers of many different rock types.

Now, it’s the Clarno “strata” which sounds like it must include more than just the nut beds.  Well, I’ll keep reading:

A small portion of these sequences [now it’s sequences?] was formed when massive walls of mud, ash, and debris came crashing down the slope of a volcano, engulfing the surrounding forest and its animal inhabitants.

Wait a second!  Just a small portion?  So far, the volcanic mud flows are all we’ve been talking about.

Over time, the mud, silt, soil, and rocks of these “lahars,” along with wood, nuts, seeds, and leaves from the forest floor, were cemented together by silica.

This cementing, or hardening of the rocks, was possibly aided by minerals from nearby hot springs. This combination left a solid cliff made up of sand, silt, and clay that encased the jumbled remains of a forest.

NO NO NO!!  This combination doesn’t leave a cliff!!  This combination leaves a rock layer.  Other stuff must happen later to form the cliff (like erosion). Plus, I’m not sure the detail about the hot springs is necessary.  Moving right along:

Within the depths of the Clarno strata is a layer of volcanic sediments deposited by a river containing some of the more remarkable mammal fossils ever found in North America.

Whoa.  Everything was mud flows, and now we have a layer of sediment deposited by a river?

Seasonal flooding swept a large variety of dead animals and plants to an existing point bar.

So now we’ve moved away from the mud flows, to ordinary flooding.  OK.  But why is there such a large variety of dead animals?  And they’re getting swept (that word again) to an existing point bar.  I guess better an existing point bar than a non-existing point bar. Fortunately, they explain what a point bar is . . .

A point bar forms when sediments, such as silt, clays, sand, and gravel, drop out as the water rounds a bend and loses energy, building up a spit of land.

Lame explanation.  I know what a point bar is, but after reading that sentence, you probably don’t.  Why does the water lose energy when it rounds a bend?  Seems counter-intuitive to me.  And it forms a spit?

With each successive flood, more sediment layers were added. Over time, these buried bones became the fossils of the Hancock Mammal Quarry.

OK.  But not much of a segue to the next paragraph:

Forty-four million years ago, central Oregon was a hot, wet, semitropical place filled with a wide diversity of plants.

Sounds like we’re starting over, eh?

Imagine a semitropical forest in the present day and a climate where there is no summer or winter, but where many of the trees seasonally lose their leaves. This is an ancient Oregon forest.

Why imagine it in the present day?  Why not imagine it 44 million years ago?

We know this based on more than 175 species of fruits and nuts that are preserved in the fossil deposits known as the Clarno Nut Beds. None of the species found here still exist. Many of the plants recovered from this assemblage have modern relatives such as walnuts, chestnuts, oaks, bananas, magnolias, and palms.

Well, OK.  And now I know what the nut beds are.

This semitropical forest echoed with the buzzing of insects; the squawks and cries of birds; and the footfalls of mammals. Most of these beasts are only vaguely familiar to us: creodonts – large meat-eaters similar to wolves or hyaenas but related to neither; Hyrachyus – a distant relative of the tapir; and brontotheres – large rhino-like plant eaters. In the swampy lakes lived crocodiles, catfish, and other organisms.

Why are we talking about animals?  I assume it’s because fossils of these animals are found along with the nuts, etc. in the mudflow beds.  Here’s their picture of the forest from 44 million years ago:

nps mural of clarno landscape that resulted in nut beds

The 40 million-year-old Hancock Mammal Quarry offers us a glimpse into a world of strange and interesting mammals.

Wait.  We were at 44 million years ago, now it’s 40.  And what’s the Hancock Mammal Quarry?

Picture a marshy stream in a warm, humid forest, where most of the plants are vaguely familiar. Dozens of strange-looking beasts gathered at this stream at different times, trampling over dead animals lying in the mud.

Didn’t we just talk about stuff like this?  And why are the live animals trampling over so many dead animals?  When I visit a stream, I don’t see any dead animals!!

The mammals that visited this backwater included Haplohippus – small leaf-eating horses; huge rhino-like animals called brontotheres; and Achaenodon – bear-like creatures similar to modern pigs. The large scavenger Hemipsalodon feasted on the carcasses, while cat-like animals hunted prey here. Why such a variety of animals were preserved at this site, but nowhere else, remains a mystery.

To top everything else, they included this very official-looking geologic section:

national park service geologic section WRONG

Look closely.  Can you see how misleading it is?  The two expanded sections that show the individual rock units are essentially the same.  They each show a large sequence of rocks that spans the time from before 40 milllion years ago to after 44 million years ago.  But each points to specific date on the time scale (OK, so the specific geologic units of interest are in red).

The top one includes more of the younger John Day Unit, while the bottom one includes more of the older Clarno Unit.   We don’t need to see the upper one at all, and the lower one should show that it covers a wide range on the timeline to the left.  There should be arrows from the Clarno Nut Beds and the Hancock Mammal Quarry pointing to specific ages (you’ll see below that I did just that).

They also posted this picture, supposedly showing the river valley environment.  The cut bank / point bar relationship is not clearly shown (it looks more like a swamp than a river).

mammalquarmural285wide nps hancock mammal quarry NOT

This entire write-up needs to be totally reorganized!.  It should go from big picture to small picture and have a coherent organization!  This is the kind of thing that gives geology a bad name.  There are great stories in geology; too bad geologists (or those writing on behalf of geologists) can’t seem to tell them.  

I know I could do better, so putting my pen to paper (so to speak), here goes:

First, the home page:

At the Clarno Unit of the John Day Fossil Bed National Monument are two distinct (and distinctly different) fossil-bearing geologic strata.  Both strata contain an incredible assortment of ancient life preserved in fossil beds.

The older strata were formed by a series of volcanic mudflows.  At the Clarno Unit, these mudflows engulfed a rich jungle ecosystem, trapping and fossilizing a wide assortment of plants and animals.

Approximately 4 million years later, a river was flowing through a broad valley in the same area.  This river valley was home to a wide variety of animals, many of which were swept away by flood waters (but then later covered up and preserved by flood-borne sediments).

OK.  I’ve set the stage.  Now, we’re ready to click to the page that provides more information . . .

It’s 44 million years ago.  Imagine a semitropical forest, filled with plants that look familiar, but nothing that quite matches a modern-day forest.  The forest also teems with animal life; once again, some may look familiar, but none of them match modern-day species.

The forest is on the flank of a volcano, which has been dormant for a long time (allowing for the development of a rich eco-system). However, trouble is brewing.  Many small tremors make the animals nervous.  Suddenly, a massive volcanic eruption occurs, the first in a series of eruptions.  Pyro-clastic debris (the term for loose rocky debris formed during an eruption) joins with water (from any snow or glaciers on the mountain top along with any lakes and streams on the mountain flanks) to form what is called a lahar, or volcanic mudflow.

This lahar moves as fast as 60 mph, and can be over 300 feet thick.  It slams into the forest, burying everything in its path.  None of the animals has a chance to escape.

The fossil remains of this forest and the forest creatures are spectacularly preserved as fossils at the Clarno Unit.

More than 175 species of fruits and nuts that are preserved in the fossil lahar deposits.  In fact, so many nuts are preserved in some of the strata that they are known as the Clarno Nut Beds. None of the species found here still exist. Many of the plants recovered from this assemblage have modern relatives such as walnuts, chestnuts, oaks, bananas, magnolias, and palms.

This semitropical forest echoed with the buzzing of insects; the squawks and cries of birds; and the footfalls of mammals. Most of these beasts are only vaguely familiar to us: creodonts – large meat-eaters similar to wolves or hyaenas but related to neither; Hyrachyus – a distant relative of the tapir; and brontotheres – large rhino-like plant eaters. In the swampy lakes lived crocodiles, catfish, and other organisms.   Fossils of all of these animals (and more) have been found in the Clarno mudflow strata.

Four million years after the devastation of the volcanic mudflows, relative peace has returned to the geologic landscape.  A broad, sweeping river has established itself in the same vicinity of the now eroded volcano.  A somewhat different assemblage of animals calls this valley home.

As the large river meanders through the valley, a system of cut banks and point bars emerges.  On the outside edge of a meander, the river flow velocity is highest, and it tends to erode away the outside bank of the river (the “cut bank.”)  Opposite the cut bank, the velocity of the water is lower, and sediment (mainly sand) tends to be deposited.  As the cut bank erodes (and moves), the point bar extends (keeping the width of the river roughly the same).

Most of the deposition in a point bar occurs during floods (just as most of the erosion of the cut bank also happens mostly during floods).  Anything carried by the river during the flood may get deposited within the sands of the point bar.  And this includes animal bones.  Because so many animals would congregate along the river, the river bed and banks become a repository for animals killed by predation as well as natural causes.

During particularly large flooding events, quantities of sand and debris ended up being deposited in point bars (including many animal bones.)

The mammals that lived in this river valley (and became fossilized) included many of the same animals fossilized in the lahar beds.  However, also found in the point bar deposits are Haplohippus – small leaf-eating horses; Achaenodon – bear-like creatures similar to modern pigs; the large scavenger Hemipsalodon that feasted on the carcasses, and cat-like animals that hunted prey.

Similar geologic river environments existed throughout the West during this same time frame. Why such a variety of animals were preserved at this site (many more than other places), remains a mystery.

Through millions of years, these point bar deposits became deeply buried and turned to stone.  Geologic upheaval uplifted these beds (along with underlying lahar deposits).  On-going erosion has exposed the rocks of the Clarno Unit. The dramatic cliffs (known as “palisades” were formed thanks to the canyon-making associated with the modern John Day River system – including Pine Creek, located along Route 218, the main access road to the Clarno Unit.

The various rock strata of the Clarno Unit are exposed in the Palisades.  These rocks (including the Clarno Nut Beds and the Point Bar fossil beds idientified as the Hancock Mammal Quarry) are represented in the following “Geologic Section:”

national-park-service-geologic-section-right

And that is that.  If I don’t say so myself:  a vast improvement!

Moving right along to more traditional ALAD fare, here’s a Panoramio shot (by cartoonasaurus) taken from the valley of Pine Hollow Creek (my watershed), less than 4 miles north of my landing:

cartoonasaurus

Here’s a shot from about 5 miles east of my landing, along the John Day River by Jerry Sturdivant:

jerry sturdivant 5 mi e on the john day

I’ll close with this shot, taken near Jerry’s (by Paolo Corradi):

paolo corradi

That’ll do it.

KS

Greg

© 2013 A Landing A Day

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