英文關鍵字
cave
column
eroded
erosion
europe
france
grotto
limestone
locations
mountain
river
stalacmites
stalactite
tourist
travel
underground
water
英文關鍵字
cave
column
eroded
erosion
europe
france
grotto
limestone
locations
mountain
river
stalacmites
stalactite
tourist
travel
underground
water