Living in an ancient flood basin, factors to consider

I dug out a French drain. Without measuring I'd say that I dug a 30 foot trench a maximum depth and width of 12 inches. I dug out 4 rocks weighing at least 50 lbs each, and probably much more.

Here's the trench:


Here's the rocks (that's a man sized hand, although probably not a Paul sized hand):


So, if you live in an ancient flood plain, and you want an easy planting, consider a raised bed. If you need some rocks for a project, consider getting out the shovel .

Looks similar to my place -- in the lowland valley with a decent size creek.. Most place I dig down a few feet, I hit a very clear layer of sand and pebbles too...