5 Then you will escape through my mountain valley, for the valley of the mountains will extend to Azal. Indeed, you will flee as you fled from the earthquake in the days of King Uzziah of Judah. Then the Lord my God will come with all his holy ones with him. 6 On that day there will be no light—the sources of light in the heavens will congeal. 7 It will happen in one day—a day known to the Lord—not in the day or the night, but in the evening there will be light. 8 Moreover, on that day living waters will flow out from Jerusalem, half of them to the eastern sea and half of them to the western sea; it will happen both in summer and in winter. 9 The Lord will then be king over all the earth. In that day the Lord will be seen as one with a single name.
34 I tell you the truth, this generation will not pass away until all these things take place. 35 Heaven and earth will pass away, but my words will never pass away. 36 “But as for that day and hour no one knows it—not even the angels in heaven—except the Father alone. 37 For just like the days of Noah were, so the coming of the Son of Man will be. 38 For in those days before the flood, people were eating and drinking, marrying and giving in marriage, until the day Noah entered the ark.
Notes and References
"... In Mark there follows a Section of eschatological predictions which has been called ‘the little apocalypse’ (13:3-37). This section is almost certainly a compilation from various kinds of materials and has been worked into a literary composition (‘let the reader understand,’ 13:14). As it stands, it contains a secret revelation given only to the four disciples first called 1:6-20). Following the tradition of prophets and apocalyptic writers it describes the catastrophes which will precede the end, not only on earth but in the heavens; but it concludes with a statement that the precise day or hour is known to no one -- neither to the angels in heaven nor to the Son, but only to the Father (13:32). This saying may reflect a post-resurrection view of Jesus as the Son; it is equally likely that he regarded himself as God’s Son in a special way and that he was expressing his faith in the Father’s purpose in spite of his ignorance of a detail. According to Zechariah 14:7 there would be ‘one day which is known to Yahweh’. This prophetic statement may lie at the foundation of the word of Jesus. If we are right in concluding that at this point Jesus was influenced by the predictions found in the prophet Zechariah, we are immediately involved in the question as to whether or not his proclamation was fully consistent. (1) It is possible to argue that different aspects of it were brought out on various occasions, and that a central core of emphasis on both present and future lies underneath the expressions found in the gospels. (2) It is also possible to suggest that, humanly speaking, ‘though he was a Son, he learned obedience by the things which he suffered’ (Heb. 5:8); his view of the coming of the kingdom was modified in relation to (a) Galilean rejection of his message, (b) his journey to Jerusalem, and (c) his experiences in Jerusalem itself We should not expect the evangelists to set forth any clear picture of such modifications. Like most ancient writers, they were not interested in psychological (or even in theological) development ..."
Grant, Robert M. A Historical Introduction to the New Testament (pp. 352-353) Simon and Schuster, 1973