In many ways this really is a scientific detective story. We have a crime scene, Mima Mounds, where the evidence, many hundreds of thousands of tons of gravel and sand vertically displaced in a regular pattern, suggests an extraordinarily large and powerful perpetrator.
And here's a tip just phoned in by some mechanical engineer playing with Google Earth -- we now have a suspect, a Pleistocene monster called 'Missoula Floods'. How do we either establish the potential connection, or clear this suspect from further investigation?
As a detective, the top three items on your investigative checklist are 'Means, Motive and Opportunity'.
- Means: Was the suspect, Missoula Floods, powerful enough to create the crime scene observed at Mima Mounds? Given the grand-scale mayhem this suspect is famous for, the modest vertical material displacements at Mima Mounds seem like a trifling distraction. But make no mistake, this suspect had the means to do this deed.
'Check' on Means, continue investigating!
- Motive: A rampaging maniac like Missoula Floods doesn't needs a motive, just the simple opportunity to commit the crime is enough provocation.
'Check' on Motive, continue investigating!
- Opportunity: To determine if the suspect had the opportunity to commit this crime, we just need to answer three simple questions:
- Proximity: Was the suspect known to be perpetrating other crimes near to where this crime was committed? The answer to this question is 'yes', Mima Mounds were formed near Olympia, Washington and Missoula Floods always finished-up an interstate rampage by running amok down in the Willamette Valley of Oregon. The distance is about 170km.
Check on Proximity for Opportunity, close enough to continue investigating!
- Timing: Were the crimes known to be perpetrated by the suspect committed in the same time-frame of the crime under investigation? Again, the answer to this question is 'yes', Mima Mounds were formed and Missoula Floods rampaged near the end of the last Ice Age.
'Check' on Timing for Opportunity, close enough to continue investigating!
- Access: Is there an access route to this crime scene that the suspect may have used? Perhaps, but the topography is challenging...170km is the distance from Oregon to Mima Mounds, but up and over an intermediate drainage divide, or ridge. We have reports from Oregon detectives that the suspect was able to scale elevations as high as 122m, and perhaps even higher.
Since we know this monster came from Montana, the 170km distance doesn't sound like a problem. What about the elevation? How high is the ridge? Is it really high enough to discourage a cold-blooded serial killer?
To finish answering the 'access' question, we need to determine the approximate minimum height of the ridge, and then check it against the suspect's known capability. The highest elevation at the lowest point of the ridge is called the 'saddle', and this is where our suspect most likely would've accessed the scene of the crime, if indeed our suspect actually committed it.
But finding the saddle was a bit easier said than done using Google Earth. The real problem is, you can find many saddles. Is the one you have just found the lowest, or do you keep looking? With some ridges, it is obvious by inspection where the saddle is. With this one, saddle candidates stretched for 15km across what I now believe to be the Main Spillway.
After some trial-and-error, at last I found a satisfactory saddle candidate at elevation 140m. This was only 15% more than the suspect's known capability, and well within the 'reported' estimates up to 180m.
So 'check' on the question of 'Access for Opportunity', and 'check' on the overall question of Opportunity!
Hydraulic Elevation Profile
But speculation about means, motive, and opportunity alone are insufficient for a conviction in any Geological Supreme Court. To obtain a conviction, we will need to find physical evidence linking the suspect to the crime scene, and the more evidence the better. To begin our search for evidence, we should consider looking at a place where we know the suspect had to be in order to access the crime scene.
And that place, in this case, is the hydraulic saddle between the Cowlitz River and Chehalis River watersheds. 'Hydraulic saddle' is an arcane engineering term that may be defined essentially as the 'lowest line of passage between two watersheds'. Of the many saddles stretching across the drainage divide, the hydraulic saddle will be the least of all in elevation.
Not satisfied with my trial-and-error estimate, I was determined to find out exactly where the hydraulic saddle occurred on the Cowlitz-Chehalis drainage divide before starting the search for actual physical evidence.
Beginning at the Columbia River near Kalama, Washington and following railroad tracks and stream-beds, I carefully traced a close approximation of the minimum, or 'hydraulic' (because that is the path that a flowing stream would follow) elevation change path up and over the drainage divide, down to Mima Mounds, and out to the Pacific Ocean at Aberdeen, Washington. When this path is plotted on a vertical scale showing elevation change, engineers call it the 'hydraulic elevation profile'.
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| Fig. 1: Hydraulic Elevation Profile from Kalama to Aberdeen. View in Google Earth |
- The hydraulic elevation profile's highest point was 132m, 8m lower than my 'trial-and-error' first approximation, and only 10m higher than the suspect's documented capability.
- More importantly, the true hydraulic saddle was about 10km west of my initial, trial-and-error estimated location.
- This turned out to be crucial in locating Goods Quarries, which are shown in the frame of the satellite image above, although I didn't actually spot them for perhaps another week.
- But in a stroke of serendipity, I did manage to locate the two quarries noted, less than 3km from the true hydraulic saddle.
Fig. 2: Goods Quarry #1
View in Google Earth - There I spotted 'scads' of interesting-looking material that bore a striking resemblance to sedimentary deposits throughout the Willamette Valley.
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| Fig. 3: Goods Quarry #2 |
- So I made an initial investigative field trip in early October 2010 that netted the name and phone number of the quarry operator. It was Sunday afternoon and the quarry gates were locked, but in another stroke of serendipity I found, in less than 30 seconds of searching, a chunk of coarse-grained 'granite' in a pile of pit run containing the tell-tale 'yellow clay' at a city park under construction nearby in Napavine, Washington.
Fig. 4: Coarse-grained 'granite' posed on basalt for reference
- Now maybe, just maybe, this granite was from a Mt. Rainier formation. But in photographs, the granite in those formations appeared fine-grained. This coarse-grained specimen I had a suspicion could very well be my first apprehended fugitive from the Canadian Rockies.
- But far more evidence would be required than one random rock, so I vowed to return during quarry operational hours to search for more. Also in this time frame Goods Quarry #3 was identified, about 8 km northwest of the first two.
Fig. 5: Goods Quarry #3 - Finally I was able to make advance arrangements with quarry owner Alan Goode, and returned on Wednesday, October 20th 2010 to begin a serious search for evidence of that Pleistocene monster called 'Missoula Floods'.
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