Various size talus is available for use in Rivers and at base of mountains. Looks real.

All the products Hobbylinc has for Talus I have purchased has all been excellent. It is exactly what you would expect. I like blending sizes and colors and other times keeping the larger ground cover in just a few areas. Roads I like best; with the fine Talus in the wheel paths with larger Talus on the out side. Makes the road look driven on. There is a great way to show tire tracks as well if your working on larger scaled diorama's like 1/48th scale or larger. At HO scale around 1/72 (scale) the road effects are harder to see. At this scale try running the small buff Talus inside and a small Talus (larger)next to it. Paint it as desired. This will still make that road look better. Also use as ground cover anywhere. It really looks great. Also I paint most ground cover so size is more paramount to me. Highly recommend.