The kind of mountain you are describing is most likely a "gentle sloping mountain" or a "shield volcano." These mountains are formed by layers of hardened lava flows and have weathered over time to have rounded peaks and gentle slopes. They are typically found in areas of low volcanic activity.
These are either VERY old mountains formed by the crust compressing or mountains formed by the crust slowly pulling apart over time.
One clue that a mountain is young is if it has sharp, jagged peaks and steep slopes. This indicates that the mountain has undergone recent tectonic activity, such as uplift or faulting. In contrast, an old mountain would have more rounded peaks and gentle slopes due to erosion over time.
A weathered mountain may appear smoother and more rounded, with less pronounced features like sharp peaks and ridges. It may also have more vegetation growing on its slopes, as weathering breaks down rock into soil that can support plant growth. In contrast, an unweathered mountain will have sharper, more rugged peaks and ridges, with less vegetation due to the harder, more barren rock surfaces.
gentle slopes
The sediment that is carried down mountain canyons and deposited on the gentle slopes at the base of the mountains is called alluvium. This alluvial deposit typically consists of a mix of sand, silt, clay, and gravel that has been transported by water flow and deposited as the flow velocity decreases on the gentler slopes.
The area is most likely due to the erosion processes, such as weathering and transportation, which wear down sharp features over time to create a smoother landscape. These processes can lead to the formation of gentle slopes and rounded mountaintops over millions of years.
Physical features of an old mountain range include worn-down peaks, rounded and eroded slopes, deep valleys, and a decreased elevation compared to when the range was young. These ranges often have a more gentle appearance due to millions of years of erosion processes shaping the landscape.
An upwarped mountain is formed when tectonic forces push layers of rock upward, creating a dome-shaped structure. They typically have broad, rounded peaks and gentle slopes. Upwarped mountains are often found in the interiors of continents and can be made of various types of rock, such as sedimentary or metamorphic.
A group of mountain slopes in one area is called a mountain range.
stalkers
Foothills or highlands are often referred to as the hilly areas near a mountain. They are characterized by gentle slopes that gradually rise from lower elevations towards the base of the mountain.