those who think it happened abruptly early in the Earth's history and those who think it happened gradually and rather later. 一派认为，它是地球史之初突然发生的；另一派认为，它是渐渐发生的，而且时间比较晚。

　　Strength of feeling runs deep on such matters. 大家在这些问题上很动感情。

　　Richard Armstrong of Yale proposed an early-burst theory in the 1960s, then spent the rest of his career fighting those who did not agree with him. 耶鲁大学的理查德·阿姆斯特朗在20世纪60年代提出早期爆炸的理论，然后花了整个余生与持不同观点的人作斗争。

　　He died of cancer in 1991, but shortly before his death he 他1991年死于癌症。但是，去世前不久，他

　　"lashed out at his critics in a polemic in an Australian earth science journal that charged them with perpetuating myths," “在澳大利亚一本地球科学杂志的一次论战中，狠狠抨击了他的批评者，指责他们使神话永久化”，

　　according to a report inEarth magazine in 1998. 据1998年《地球》杂志报道说。

　　"He died a bitter man," reported a colleague. “他死不瞑目。”一位同事说。

　　The crust and part of the outer mantle together are called the lithosphere (from the Greek lithos, meaning "stone"), 地壳以及部分外层地幔，统称岩石圈（源自希腊语lithos，意思是岩石）。

　　which in turn floats on top of a layer of softer rock called the asthenosphere (from Greek words meaning "without strength"), 而陆界又浮在一层较软的岩石之上，名叫软流圈（源自希腊语，意思是“没有力量”），

　　but such terms are never entirely satisfactory. 但这些名称向来不令人满意。

　　To say that the lithosphere floats on top of the asthenosphere suggests a degree of easy buoyancy that isn't quite right. 说岩石圈浮在软流圈上面，意味着有一定程度的浮力，这是不完全正确的。

　　Similarly it is misleading to think of the rocks as flowing in anything like the way we think of materials flowing on the surface. 同样，认为岩石在像平面流动的物体那样流动，这也会使人产生误解。

　　The rocks are viscous, but only in the same way that glass is. 岩石是黏稠的，但只是很像玻璃。

　　It may not look it, but all the glass on Earth is flowing downward under the relentless drag of gravity. 这似乎不大可能，但在引力的持续拉动下，地球上所有的玻璃都在往下流动。

　　Remove a pane of really old glass from the window of a European cathedral and it will be noticeably thicker at the bottom than at the top. 从欧洲教堂的窗户上取下一块真正古老的玻璃，你会发现它的底部明显厚于顶部。

　　That is the sort of "flow" we are talking about. 我们在讨论的就是这种“流动”。