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A molehill (or mole-hill, mole mound) is a conical mound of loose soil raised by small burrowing mammals, including moles, but also similar animals such as mole-rats, marsupial moles and voles. They are often the only sign to indicate the presence of the animal. Molehills are waste material which come from digging or repairing burrows, and so are usually found where the animal is establishing new burrows, or where existing ones are damaged (for example by the weight of grazing livestock). Where moles burrow beneath the roots of trees or shrubs, the roots support the tunnel, and molehills are less common, and so even a dense population of the animals may be inconspicuous in these places. Molehills commonly occur in lines along the route of the burrow, but in some cases they may not be directly above the burrow itself but at the ends of short side-tunnels. The mole runs vary in depth from surface runs only a few inches deep, to main runs, some 12 to 18 inches deep Molehills are sometimes used as a source of fine soil for use in gardening. Particularly they are valued by some practicians of permaculture for the fine potting soil produced by the moles' claws. Molehills have an important benefit to soil by aerating and tilling it, adding to its fertility. However, they may cause damage to gardens and areas of grass (such as golf courses), and represent a minor safety hazard. Where mole-hills are not desired, the moles may be killed, or the fresh molehills may be removed carefully as soon as they appear. This leaves the animals and their galleries undamaged and thus reduces the need for the moles to make further molehills when they clear earth out of the tunnels. Recording molehills may be the only reliable way to determine the number of moles in an area. The common phrase "to make a mountain out of a molehill" (meaning to exaggerate a minor problem) stems from this soil's name.〔https://www.psychologytoday.com/blog/headshrinkers-guide-the-galaxy/201312/how-make-mountain-out-molehill〕〔http://www.thefreedictionary.com/make+a+mountain+out+of+a+molehill〕 File:Mol 1.jpg File:Mol 2.jpg File:Mol 3.jpg File:Mol 4.jpg == References == 〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Molehill」の詳細全文を読む スポンサード リンク
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