One of the things which makes it so long is the "little apocalypse," with which Mark culminates the events of that day. Here it is.
Then Jesus began to say to them, “Beware that no one leads you astray. Many will come in my name and say, ‘I am he!’ and they will lead many astray. When you hear of wars and rumors of wars, do not be alarmed; this must take place, but the end is still to come. For nation will rise against nation, and kingdom against kingdom; there will be earthquakes in various places; there will be famines. This is but the beginning of the birthpangs.
“As for yourselves, beware; for they will hand you over to councils; and you will be beaten in synagogues; and you will stand before governors and kings because of me, as a testimony to them. And the good news must first be proclaimed to all nations. When they bring you to trial and hand you over, do not worry beforehand about what you are to say; but say whatever is given you at that time, for it is not you who speak, but the Holy Spirit. Brother will betray brother to death, and a father his child, and children will rise against parents and have them put to death; and you will be hated by all because of my name. But the one who endures to the end will be saved.
“But when you see the desolating sacrilege set up where it ought not to be (let the reader understand), then those in Judea must flee to the mountains; the one on the housetop must not go down or enter the house to take anything away; the one in the field must not turn back to get a coat. Woe to those who are pregnant and to those who are nursing infants in those days! Pray that it may not be in winter. For in those days there will be suffering, such as has not been from the beginning of the creation that God created until now, no, and never will be. And if the Lord had not cut short those days, no one would be saved; but for the sake of the elect, whom he chose, he has cut short those days. And if anyone says to you at that time, ‘Look! Here is the Messiah!’ or ‘Look! There he is!’ —do not believe it. False messiahs and false prophets will appear and produce signs and omens, to lead astray, if possible, the elect. But be alert; I have already told you everything.
“But in those days, after that suffering,
the sun will be darkened,Then they will see ‘the Son of Man coming in clouds’ with great power and glory. Then he will send out the angels, and gather his elect from the four winds, from the ends of the earth to the ends of heaven.
and the moon will not give its light,
and the stars will be falling from heaven,
and the powers in the heavens will be shaken.
“From the fig tree learn its lesson: as soon as its branch becomes tender and puts forth its leaves, you know that summer is near. So also, when you see these things taking place, you know that he is near, at the very gates. Truly I tell you, this generation will not pass away until all these things have taken place. Heaven and earth will pass away, but my words will not pass away.
“But about that day or hour no one knows, neither the angels in heaven, nor the Son, but only the Father. Beware, keep alert; for you do not know when the time will come. It is like a man going on a journey, when he leaves home and puts his slaves in charge, each with his work, and commands the doorkeeper to be on the watch. Therefore, keep awake—for you do not know when the master of the house will come, in the evening, or at midnight, or at cockcrow, or at dawn, or else he may find you asleep when he comes suddenly. And what I say to you I say to all: Keep awake.” ~ Mark 13:5-37Sovereign and Mighty God, we pray for those...
... who are being led astray; may they find your path.
... who are experiencing birthpangs; may the fruits of their labor bring them joy.
... who are brought before councils to be tried; may they speak your truth.
... who are beaten becasue of who they are; may you heal their wounds of body and spirit.
... who have been betrayed by their own kin; may you be their strong defender.
... who offer themselves as false messiahs; may the light of Christ convert them.
... who suffer; may they be able to tell their stories.
... who feel that it is the end of the world; may you show them life on the other side.
... who long to hear your eternal words; whisper in their ears.
... who need to keep awake; give them good company for the vigil.
We pray in your name, holy, holy, holy Lord. Amen.