A Scandinavian folk belief that lightning frightens away trolls and jötnar appears in numerous Scandinavian folktales, and may be a late reflection of the god Thor's role in fighting such beings. In connection, the lack of trolls and jötnar in modern Scandinavia is sometimes explained as a result of the "accuracy and efficiency of the lightning strokes". Additionally, the absence of trolls in regions of Scandinavia is described in folklore as being a "consequence of the constant din of the church-bells". This ring caused the trolls to leave for other lands, although not without some resistance; numerous traditions relate how trolls destroyed a church under construction or hurled boulders and stones at completed churches. Large local stones are sometimes described as the product of a troll's toss. Additionally, into the 20th century, the origins of particular Scandinavian landmarks, such as particular stones, are ascribed to trolls who may, for example, have turned to stone upon exposure to sunlight.