How do I stop extremely glossy and reflective landscapes?

I’ve made my own landscape with three different texture layers. After creating mountains I get a really annoying problem that I can’t seem to fix. My mountains are extremely reflective. Below is the materials and also a snip of what the glossy mountains look like. I got it to look slightly better by making the level darker, but I’d rather just keep it daytime and have no gloss. I think there’s a node I should be messing with in my material editor but after searching for ages I really don’t know what to do.

Use Roughness and Specular inputs. If you dont have roughness maps, first try 0.9 for roughness. If it doesnt give the desired result then plug another constant(0.4 - 0.3 should do) to specular as well.

That fixed it nicely, much appreciated