a prehistoric megalith typically having two upright stones and a capstone. 它是指用石架成的史前墓石牌坊，此石架是由两块直立的石头和一块顶石搭成的。
A prehistoric megalithic structure consisting of two or more upright stones with a capstone, typically forming a chamber. 石棚常作寝室的史前巨石结构，由二块或多块矗立的石头和一块覆盖的石头构成
