Challenge day 3

Attempted a Canadian Rockies landscape with a river. I'm struggling with understanding how to add depth to the mountains, they look flat and incomplete but most adjustments I made didn't help my cause. Additionally, I had no idea fill in the landscape between the river and the trees in the foreground. The boulders I tried to make looked like oddly placed bits of powder and I couldn't manage to make grass in any convincing way. The glass is square but I had to shoot from an angle to prevent the lights reflection blocking the image. I'm pleased with how the pine tree branches on the front right corner came out.