Beautiful work!!!
Very nice work!! Keep working!!

Nice work. Kinda wish there was a bit more space at the top.

I think, the concept is really good.
Is it possible that we see the wireframe of the rocks?
Was it on purpose to use this as texture?
Looks like detailed modeling

no, i dont think that is the wire framing, it is just the way the texturing took place on the wire frame

This is so pretty. I can tell your going to be really good at this. How? Well look at what youre admiring when youre doing your pictures how beautiful the earth is and its creation in all things.
If you dont mind again I will say a little on landscapes.

Landscapes are usually meant for a camera view from a long view. Thats what gives the water its natural look. When your taking closer shots in on landscapes you have to make your texture scaling so large that when rendered it looks like its from a distance. But it can confuse your lighting because naturally distance alters shadows. So you can fool yourself.
This is beautiful though. Keep doing it and dont give up.

The texture things are not so hard at all. Find a calender and admire some landcapes for a minute. Try to mimic it...if you dont know how to do it in Bryce.
Im at work now when I am saying this but...
On the materials dialog where the three flat pictures are there is one that brings up the three spheres that are for scaling, rotation, and positioning. The top one. if you increase it on X,Y,Z you can change the scaling of your textures. The individual areas can be used for scaling in a particual direction.
For instance on a metal if you add a bump map...and increase the x levels you can make brushed metals.

If you increase the Y values on Water and tweak it right you can create waterfalls.

X,Y,Z values are basically from Geometry. So its good to pay attention to Math. because it helps with understanding depth and objects in the world. I despised Geometry but then realized I needed it so much to do art and design. They give you understanding of function and measurement in space.

X means left and right
Y means Up and down
Z means back and forth