"Surrounding hills" refers to hills or elevated areas that are located in close proximity to a particular place or region. These hills encircle or border the mentioned area. Full definition
The two areas share the characteristic of both being in the path of water flowing from surrounding hills. (journals.plos.org)
Even when then wind is blowing strong the vistas of surrounding hills and mountains look similar to what you'd see in Los Angeles. (geoengineeringwatch.org)
In contrast, the smaller dark spots (which can appear as gray, brown, or red) may be the remains of low - speed, carbon - rich asteroids that splattered such» deposits» onto Vesta's surface, or they may be the result of higher - speed asteroid that melted and darkened volcanic basaltic crust on crater walls and floors, or on surrounding hills and ridges (NASA DAWN news release). (solstation.com)