The best evidence for the layered-mantle thesis is the well-established fact that volcanic rocks found on oceanic islands,islands believed to result from mantle plumes arising from the lower mantle,are composed of material fundamentally different from that of the mid-ocean ridge system, whose source,most geologists contend,is the upper mantle.
您真厉害。。
(be) believed to do
我感觉这个believed是过去式的相信吧
您的意思是省略了be的被动?
对,不是过去时,是过去分词。 (be)believed to 举个例吧: Leifeng, believed to be an honest, is always ready to help others.= Leifeng, who is believed to be..., is...