Building terraces

I've been building some terraces by hand, using black locust slab wood instead of building stone walls. The slope is very muddy with almost pure clay soil. I'm hoping the terraces will spread and slow the flow of water so that I can grow more trees and plants. Anyone else have experience using terraces on wet hillsides?
Here's the video of my son working on the terraces

I wish you success with the project. I think, were it me in what I can see of your situation, I would have gone for the "net and pan" approach on such a steep grade.
It would involve less work, less disturbance and is an approach Lawton suggests for slopes too steep for swales.

I will suggest that you get a good cover crop seeded on those terraces as soon as possible, to hold things together when spring rains arrive.

Peter - what is the "net and pan" approach? Got a link for it?

Michael Cox wrote:Peter - what is the "net and pan" approach? Got a link for it?

I believe I first heard it from Lawton. The idea is, essentially, a web of trenches and pits. You plant trees in the pits and run trenches linking the pits. Generally done as a diamond pattern covering the steep slope. A quick google search produced links to several discussions here on permies, showing that Brad Lancaster talks about the method in his water harveting book, and Toby Hemenway discusses it in Gaia's Garden.

When I say trenches and pits, think in terms of shallow trenches and hollows, not WWI defensive earthworks

The end result is a water harvesting net across the slope that feeds both water and organic matter carried by the wate into the hollows where the trees are planted. The trees will aid in stabilizing the slope, while the relatively minimal earth moving does not destabilize as much as terracing would.

Would you recommend the net and pan approach even if it is a very wet site? That bank is extremely wet with saturated clay soil 10 or 11 months a year. Occasionally in a dry summer, it's not muddy, but the springs on our hill keep it wet most of the time.
I am going for the opposite of a trench, I am hoping to have berms for the trees to grow on top of.
I think I might be in the opposite situation of Geoff Lawton, who works a lot with arid climates. Here we are inundated with water. I'm curious to hear your thoughts on this, as I will be clearing a lot more of that bank and trying to make it more suitable for trees to grow.
I don't mind the work of terracing, it only took about 25 minutes to dig out a 60-70 foot terrace.