the entrance to gondolin has some general similarity to the far fuller and more precisely visualised account in the later tuor : a deep river-gorge , tangled bushes , a cave-mouth -- but the river is certainly sirion ( see the passage at the end of the tale , p. 195 , where the exiles come back to the entrance ) , and the entrance to the secret way is in one of the steep river banks , quite unlike the description of the dry river whose ancient bed was itself the secret way ( later tuor pp .