This particular digging operation was inspired by a mistake. Instead of getting lots of small stones for the Kelly memorial zen garden, we got a bunch of really big river stones. Useless for that project, but we do still have lots of work to do on erosion-proofing the driveway and yard. Thus, this experimental idea:
Dig a trench with a flat bottom, water enters and loses velocity as there is no elevation change for gravity to pull it down. Culverts, ditches, gutters – these are all things that are quite similar. But we had river rock, and dumped that in.
River rock like this is, as the name implies, rock that lines the bottom of rivers. It’s smoothed by the water, but too heavy to be moved, so it ‘armors’ the bottom of rivers naturally, preventing deeper erosion. It is not really usable in most human structural uses because unlike jagged rock, it will always shift and move around – crushed limestone driveways hold almost like cement, but can be eroded, this can’t be eroded but won’t hold anything. Here we use it as part of the driveway, the limestone provides the structure, and this bit provides a water flowing channel to reduce erosion (where this trench is, there had been a little trough eroded during the last torrential rain).
And perhaps most interestingly, here is the stratigraphy of the gravel driveway:
