With all the rain, it was no surprise. Mudslides are somewhat common here, and they sometimes close roads. In fact, we were sort of expecting a small mudslide almost in this particular spot right when we got the call about it. The only slight surprise was that it was right next to where we expected it to be. The cliff that we expected to make this sort of mess was still intact under the tarps put over it to deflect some of the rain.
Fortunately, it was a small mudslide that blocked only one lane. We were able to direct traffic through the other lane while the blocked lane was cleared of debris by a small bulldozer.
The top of the cliff slid to the bottom along with a stump of a Douglas fir that was cut down many years ago. The Douglas fir was cut down so that it would not destabilize the soil that it was rooted into as it moved in the wind. However, The soil was destabilized as the Douglas fir roots that held it together decayed. This is actually a common dilemma, since trees sometimes need to be cut down before they cause such problems, but the death and decay of the roots of such trees ultimately cause the same problems.
The sorts of trees that could be coppiced do not do so well in the dry soil on top of cliffs. Otherwise, we could plants willows, cottonwoods or something of the sort, and cut them down as they get too big, without killing the roots. They would be happy to regenerate and continue the process. The sorts of plants that prevent surface erosion do not do much to stabilize the soil. Otherwise, we could put something as simple as freeway iceplant (Carpobrotus chilensis) on top, and let it cascade downward over the unstable area.
1. It was nothing too serious, but just enough to block the inbound lane. Tarps over the cliff that we expected to make this sort of mess are visible above the retaining wall just beyond. My work pickup in the lower right corner of the picture blocked the inbound lane with its headlights and hazard flashers on. I directed incoming traffic around it into the clear outbound lane as it was available. The young man off in the distance moved his pickup out of the outbound lane, and also directed traffic accordingly. When necessary, he stopped traffic while incoming traffic used the outbound lane. We communicated by radio and hand signals.
2. This is the stump of the Douglas fir that was cut down so that it would not dislodge the soil and cause a mudslide. A decayed stump of a smaller madrone tree is to the right. Their rotting roots and the English ivy were insufficient to stabilize the top of the cliff.
3. These significant mudstone boulders on the far side of the road could have done some serious damage to a car if one had gotten in their way.
4. That is where the Douglas fir stump came from, just to the left of the drainage pipe. It did not get very far. That is it at the lower left corner.
5. We arrived about ten. By noon, there was not much evidence of what had happened. We left the cones because the road was slippery with mud.
6. This is supposed to be a gardening blog, so here is an unidentified fern that witnessed the whole ordeal from a stable portion of the same cliff. There is slightly more flora to this story than two dead stumps and a bit of ivy.
This is the link for Six on Saturday, for anyone else who would like to participate:
https://thepropagatorblog.wordpress.com/2017/09/18/six-on-saturday-a-participant-guide/
Tony Tomeo 
Wow that is steep! No wonder things struggle to cling on. It must be difficult to manage. Glad no one was hurt.
LikeLiked by 1 person
Natives know how to cling to steep hillsides. This is more of a cliff because the roadway was cut into the already steep hillside over the canyon.
LikeLiked by 1 person
Seeing the mud, the slope, and these landslides, I understand that you had a lot of rain (as you have already said in old SoS ….) Abnormal quantity or normal for the season?
LikeLiked by 1 person
Yes . . . sort of. The weather here is as variable as it is anywhere else. There has been quite a bit more rain here than there normally is, but it has been worse in past years.
LikeLiked by 1 person
We ususally hear about mudslides only when a big one closes the PCH or some such, and we never get any details about how they happen. I enjoyed the details here, such as this: “The sorts of plants that prevent surface erosion do not do much to stabilize the soil.” Very interesting.
LikeLiked by 2 people
As you can understand, surface erosion is a common concern as well. We like to use dense ground covers for that, although such ground covers do not get established in every situation where they are needed. Plants with aggressive roots that would be bad around concrete are useful for slope stabilization, as long as the trees associated with such roots do not get too big.
LikeLike
It’s very interesting to see all the details behind this mudslide. I have been following the avalanches that are closing the highways in Colorado. While that is a natural and somewhat regular occurrence for them, this year has been extreme.
And like your above commenter, your details are great. No matter what you’re writing about, I always learn something!
Karla
LikeLiked by 1 person
Thank you. I figured that I were to write about mud, I should at least try to make it interesting.
LikeLiked by 1 person
I did not realize you were from California! Wow! That could have been a disaster! It did not take them very long to clean up the area though! Great fern!
LikeLiked by 1 person
This was a small one. Some are big enough to block two lanes of Highway 17. A few years ago, all four lanes were blocked! Mudslides sometimes take houses with them. There happens to be a house just a few yards from where this stump slid from, but it does not worry me much.
LikeLiked by 1 person
Always interesting topics on your blog, Tony.
LikeLiked by 1 person
Thank you; although it is just mud.
LikeLike
Incredibly interesting! And thanks for the token plant at the end. 😁
LikeLiked by 1 person
Thank you. I did not think that mud would be so interesting.
LikeLike
‘Mud, mud glorious mud! There’s nothing quite like it for thinning the blood.’ It’s a very old song from a very old British double act. It’s probably on YouTube somewhere! Great story and glad there were no casualties.
LikeLiked by 1 person
There is someplace in the Southeast of North America that was known by the native American Indian name of ‘Mud and More Mud’. I can not remember the name. Nor can I remember when it is. It would be interesting to find.
LikeLiked by 1 person
You do seem to get some extreme weather and effects down your way!
LikeLiked by 1 person
Our weather is actually famously mild, and we are just a few miles from the chaparral climate of the Santa Clara Valley. However, we do happen to be in some rather steep and seismically active mountains that are regularly destabilized by weather and seismic activity. The mountains are not very high at all; but are steep and dynamic.
LikeLiked by 1 person