I have a shapefile with contours for a Brazilian state. The contours give me the elevation across that particular state.
My goal is to use the contours to identify hills. Ultimately, I would like to create polygons around hills.
Initially, I thought about dividing the Brazilian state into small grids, calculate the mean elevation in the grid, and then identify hills by looking at the grids with high elevation. However, this approach does not seem to take into consideration the relative aspect of hills (they have higher elevation relative to other areas immediately next to it, but can still have lower altitude relative to areas on the other side of the state, for instance).
It seems that the contours are able to capture the presence of a hill relative to the elevation of the terrain in the surrounding areas: "Concentric circles indicate a hill. When contour lines form closed loops all together in the same area, this is a hill. The smallest loops are the higher elevations and the larger loops are downhill" (https://courses.lumenlearning.com/sanjac-earthscience/chapter/topographic-maps/#:~:text=Concentric%20circles%20indicate%20a%20hill,the%20larger%20loops%20are%20downhill.).
My goal is to find these "concentric circles" and draw a polygon around them.
My question is somewhat similar to these ones, however, I am hoping to perform the task using R (or QGIS, although with difficulty), as opposed to python or ArcGis:
I am extremely new to GIS and have never dealt with contours before, so I apologize if the question is too basic.