Tag: geology

More rocks – Detroit Lake

Yesterday Shelby, Kris, our three dogs and I went walking along the almost dry bed of Detroit Lake. We started at Hoover Campground and walked upstream next to the Santiam River which feeds Detroit Lake.

  
The travel was mostly smoothed cobblestones with some sand as the lake level is extremely low due to lack of rain and snow melt. 

Below you can see the bed of Detroit Lake. The post behind Kris is a No Wake sign.

  
At this point we should be 20 feet underwater. 🙁

  
The dogs were allowed to run off leash as we were the only ones out there. When we did see others we leashed until past them.

  
The sheer diversity in the rocks we walked on was amazing. I took pictures of a few for this post. The cobbles ranged from granite to volcanic to sandstone.

 These green stones were interesting because most of them were very brittle. They were green all the way through and I have no idea what the composition is.

 
Here you can see sandstone that was laid down with various layers of a darker material. Most likely due to ash or dust in the sky. Could also be from a flash flood event where this rock was formed higher up a bank or shore where only silt settled out.

   
There were also a number of these types where it was a compressed mix of larger pebbles and sand. Very interesting! 

   
The below conglomerate has bits of granite and sandstone mixed inching you can see at the lower right of the rock as the darker spot.

 

Here is another sandstone rock that had two different colors of sediment compressed into it. There were a number of these out there.
  

Geology – My Secret Pashion

I love rocks. I love gazing and wondering about the various layers I see on cutouts during drives. I love to postulate on what happened when and why.

For example in central Oregon it is high dessert. There is water in the ground but it’s deep and the top layer is not hospitable for most plant life. However the water that does run through has cut deep canyons over the years.

Through various flooding events and geologic processes the layers are amazing. Most of the top layers are volcanic. Examples of dormant volcanoes can still be seen on the horizon.

Mt Jefferson in the distance.   
Black Butte, Three Fingered Jack, Mt Washington and the Three Sisters.


The top layer in some parts is soil similar to sand and very dusty. You can see above that the vegetation is sparse and short. Sage brush and short pines that have deep roots. This spot is looking towards the Deschutes River and West.

  
This is the Crooked River and looking East. You can see the different layers of sediment and volcanic events.

   
This cut on the road down to the Cove Palisades Marina is really interesting. The bottom layer consists of large cobblestones that were laid down during a flooding event of great magnitude. Then this thin layer of gold sediment, probably from a distant event that blew dust or ash into the sky that spread?

 
The next layer is finer sediment that will crumble if scraped (I did!). You can see larger cobbles every now and then mixed in that larger layer of fine sediment. Then a volcanic event laid down a layer of lava. Then you have the picture below of a random bit of fine sand of a white color. I’m sure some of this is from glacial retreat but I don’t know which. Perhaps the large base layer of cobbles is from a glacier and the finer is from melt water?

  
You can see both the Deschutes and Crooked River in the below picture. Deschutes in the distance and Crooked front and center. Cove Palisade is the confluence of the Deschutes, Crooked and Metolius Rivers.

  
This whole area is really flat except for the canyons created by these rivers. It’s such an interesting area.

   
  
At this time of year the weather has been dryer than normal and as a result there are several large fires raging. In the picture below the clouds and haze are from the Warm Springs Reservation fire to the North.

  
And through all this Twitch was tagging along. I got tired of him being spastic on my lap and relegated him to the floor boards.