| en natural obstacle (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en gorge (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en escarpment (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en natural obstacle (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en forest (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en steep slope (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en river (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en swamp (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en watercourse (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||
| en gully (n) | 
         
            ― IsA ⟶
         
        
            Weight: 1.0
         
     | 
    
        
 | 
    Source: OpenCyc 2012 | ||