Watching the Ground Shift

I love survey monuments (aka markers, aka marks). They get planted in the ground so that surveys can be done from exactly the same spot, at different times. If you measure from the same place over time, you can detect changes in ground position by comparing the surveys. If you don’t use the same place, you get bupkis*.

Walking the dog, I discovered that a neighbor has a monument on his property:

Wait - is that a monument?

Wait – is that a survey monument?

Interesting! According to the inscription, at one time the City of Los Angeles held sway over this area. (No longer.) And I didn’t know they printed the elevation on the monuments back then. Fancy!

"Elevation 1716.15 feet above sea level"

“Elevation above sea level 1716.15 feet”

I wonder if the neighbor got special instructions when he bought the house, forbidding him from messing with the monument. I wonder if that irritated him – gub’ment can’t tell me what to do! – or maybe he’s like me, and enjoys the connection with local history. Whoever first planted the monument is surely gone by now, the monument has been there for generations. Not all the monuments have led such sheltered lives. Monuments about a mile east got buried in a 1934 debris flow:

 

Photo from Mike Lawler, Crescenta Valley Historical Society

Photo from Mike Lawler, Crescenta Valley Historical Society

Admittedly, most surveys are done for boring reasons like defining property lines. But they can also reveal a region’s geology, its ground deformation – I love that term! – the movements related to earthquakes, subsidence, landslides. Given enough time, this monument will have quite a story to tell. After all, it’s because earthquakes are shoving the mountains skyward that I have a mountain view from my house:

 

Mountains going up, valley going down: earthquake country.

Mountain view courtesy of earthquakes.

Obviously I am fascinated by these hazards but it would be fine with me if, during my years in this house, I experience no geologic drama.

* Looking up this spelling, I discovered that bupkis means goat droppings! One really can learn something new every single day!

A recent WP Weekly Photo Challenge wanted to see a monument.

Advertisements

The Daily Prompt: The Zone – Digging for Boulders

I love to dig in my garden. My neighborhood lies in the foothills of a mountain range, so all the yards are full of rocks of many sizes which were shed from the mountains in ancient landslides.

When I dig a hole for a new plant, I am a rock archaeologist, discovering buried artifacts. Except I don’t have to be careful where I slam my shovel. Sometimes the rock is so weathered that I can pull it apart with my hands, exposing fresh glittering crystals in the local granite (technically a granodiorite, for other rock nerds).

When the shovel catches and bends, I know I’ve caught a big one. A boulder. Then I dig from many angles, eventually on my knees with my hands, to excavate it. Often a rock is lodged in place against several other rocks, still locked and buried.  I have to use my fingers deep inside the hole to figure out which rock to move next in order to  release my target.  So removing a lodged-in-place rock requires working a 3D puzzle with your eyes closed.

And when I finish the puzzle, I have a hole for my plant and new borders for my garden.

The undug.

The undug.

This post topic comes from The Daily Prompt.