In a slump

I'm trying to work through a painting slump, and trying different approaches. Here's another limited palette painting, just white, ultramarine blue yellow ocher, and maybe a touch of burnt sienna, I can't be sure. The idea for me was to concentrate on values. Painted on the cheapest piece of throw away cardboard I could find (packaging from an Ikea shelf, I've got a nice stash to play with now!).

Berkeley Hills, just off of Claremont. 6x8 Oil on cardboard.

Here's another that started out with the limited palette, and then at the end, I added a little light green to the hillsides. I was surprised how close I could get to the vibrant green value with just blue and ocher. The added green helped to give a little pop to the foreground. Both of these were done on pretty hazy days, I'm curious if this palette will work in different lighting conditions. I'll be trying different color combinations, so we'll see what shakes out.

TildenPark along the Skyline trail. 6x8 O/P