Skeptics of the New Testament usually assume a long gap exists between the events in the gospels and the recording of the events in writing, They further tend to assume that the first source of writing about these events was the gospel of Mark. Thus they assume events were exaggerated and miracles were made up and so on during this gap period. In this essay I am going to dispel this myth by demonstrating that there were written records of the gospel events that existed before the writing of Marks gospel. I will further demonstrate that there were multiple sources transmitting the information. Mark's was not the first gospel written but merely the first of the canonical gospels to be written. None of the early works survive in MS form but we find traces of them in copies of latter works.
Traces of Gospel Material in Gap
(1) Oral tradition
(2) saying source Material
(3) Non canonical Gospels
(4) traces of pre Markan redaction (PMR)
(canonical material that pre-date Mark, assumed the to be the first Gospel, also called Pre Mark Passion narrative PMPN).
(1) Oral Tradition (in Two Major Sources)
Scholars have always recognized that the telling of the gospel stories began with the transmission of oral tradition. Of course the problem with oral tradition is that it'snot written, Once written it becomes written tradition. Yet the form of the oral transmission can cling to the writing, It is possible to identify sources of oral tradition even when written down. We see oral tradition reflected in the New Testament in two major sources:
The great scholar Edgar Goodspeed held that oral tradition was not haphazard rumor but tightly controlled process,and that all new converts were required to learn certain oral traditions and spit them back from memory:
Our earliest Christian literature, the letters of Paul, gives us glimpses of the form in which the story of Jesus and his teaching first circulated. That form was evidently an oral tradition, not fluid but fixed, and evidently learned by all Christians when they entered the church. This is why Paul can say, "I myself received from the Lord the account that I passed on to you," I Cor. 11:23. The words "received, passed on"  reflect the practice of tradition—the handing-down from one to another of a fixed form of words. How congenial this would be to the Jewish mind a moment's reflection on the Tradition of the Elders will show. The Jews at this very time possessed in Hebrew, unwritten, the scribal interpretation of the Law and in Aramaic a Targum or translation of most or all of their Scriptures. It was a point of pride with them not to commit these to writing but to preserve them.In my essay :Community as author" I will deal with the validity of oral tradition At this point I give examples of the traces of oral tradition in Paul's writings: 1 Corinthians 15:3-8 has long been understood as a formula saying like a creedal statement.
"For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures;
1Cr 15:4 And that he was buried, and that he rose again the third day according to the scriptures:
1Cr 15:5 And that he was seen of Cephas, then of the twelve:
1Cr 15:6 After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep.
1Cr 15:7 After that, he was seen of James; then of all the apostles.
1Cr 15:8 And last of all he was seen of me also, as of one born out of due time.
Two problems: (1) Doesn't conform to a canonical reading; (2) seems to contradict the order of appearances of the epiphanies (the post resurrection sightings in Gospels--in fact doesn't even mention the women, ). Nevertheless it is in general agreement with the resurrection story, and seems to indicate an oral tradition already in circulation by the AD 50s, and probably some time before that since it has had tome to be formed into a formulation statement. This is because Paul was writing in the 50s. These are clear references to events mentioned in the Gospels written decades before the Gospels were written,
Second major source o oral tradition:
(B)The nature of pericopes
Pericopes are little story units we find imn the Gospels like the good Samaritan. The nature of the pericopes themselves shows us that the synoptic gospels are made up of units of oral tradition. Many skpetics seem to think that Mark indented the story in the Gospel and that's the first time they came to exist. But no, Mark wrote down stories that the church had told for decades. Each unit or story is called a "pericope" (per-ic-o-pee). T?his is "A term used in Latin by Jerome for sections of scripture and taken over by Form Critics to designate a unit, or paragraph, of material, especially in the gospels, such as a single parable, or a single story of a miracle." Terence C. Mournet tells us, "Dunn Suggests, during the course of his investigations, that the variation within the pericopes under examination is reflective of is reflective of their indebtedness to the oral transitioning process described by Bailey where traditions are changed (flexible) during their retelling but remain within the boundaries established by the communities."  There is room in oral form or a minor variations but along an agreed upon range, the rage is no doubt set by the first telling of the eye witnesses and what the community certain it originally heard. That range of agreement constitutes a control om the dissemination of information
On this basis Baultmann developed "form criticism" because the important aspect was the form the oral tradition too, weather parable, narration, or other oral form.
(2) Saying Source Material
The saying source was the forerunner of the narrative Gospel. Church father Papias who studied with Apostle John said that Matthew first wrote his gospel as a list of Jesus' teachings in Hebrew,called The Loggia. There's hypothetical Q source, Gospel of Thomas,k Egerton 2 and others. Here I will focus just On Thomas, and deal with others in part II. We see traces of pre Mark redaction imn all of those I just mentioned (except Loggia we don't have a copy)..
A. Gospel of Thomas
The Gospel of Thomas which was found in a Coptic version at Nag Hammadi, but also exists in another form in several Greek fragments, is a prime example of a saying source. The narratival elements are very minimal, amounting to things like "Jesus said" or "Mary asked him about this,and he said..." The Gospel is apt to be dismissed by conservatives and Evangelicals due to its Gnostic elements and lack of canonicity. While it is true that Thomas contains heavily Gnostic elements of the second century or latter, it also contains a core of sayings which are so close to Q sayings from the synoptics that some have proposed that it may be Q (see Helmutt Koester, Ancient Christian Gospels). There are 46 sayings that parallel Q sayings in Thomas. This is what I call the orthodox core of the book.
Be that as it may, there is good evidence that the material in Thomas comes from an independent tradition,t hat it is not merely copied out of the synoptics but represents a PMR. Through Statistical Correlation Analysis of Thomas and the Synoptic, Steven Davies argues that the Gospel of Thomas is independent of the canonical gospels on account of differences in order of the sayings.  Lisa Haygood of Fullerton states "serious probability exists that Thomas preserves an older tradition of the historical Jesus than that of the synoptic Gospels."  Stephen J. Patterson compares the wording of each saying in Thomas to its synoptic counterpart with the conclusion that Thomas represents an autonomous stream of tradition:
If Thomas were dependent upon the synoptic gospels, it would be possible to detect in the case of every Thomas-synoptic parallel the same tradition-historical development behind both the Thomas version of the saying and one or more of the synoptic versions. That is, Thomas' author/editor, in taking up the synoptic version, would have inherited all of the accumulated tradition-historical baggage owned by the synoptic text, and then added to it his or her own redactional twist. In the following texts this is not the case. Rather than reflecting the same tradition-historical development that stands behind their synoptic counterparts, these Thomas sayings seem to be the product of a tradition-history which, though exhibiting the same tendencies operative within the synoptic tradition, is in its own specific details quite unique. This means, of course, that these sayings are not dependent upon their synoptic counterparts, but rather derive from a parallel and separate tradition.There are several other non canonical Gospels perhaps the most important for apologetic is Gospel of Peter and I will deal with thyiat and others in part II.
B. evidence of saying source in Pauline references
Koster theorizes that Paul probably had a saying source like that of Q available to him. Paul's use of Jesus' teachings indicates that he probably worked from his own saying source which contained at least aspects of Q. That indicates wide connection with the Jerusalem chruch and the proto "Orthodox" faith.
|Parable of Sower||1 Corinthians 3:6||Matt.|
|Stumbling Stone||Romans 9: 33||Jer 8:14/Synoptics|
|Ruling against divorce||1 cor 7:10||Mark 10:11|
|Support for Apostles||1 Cor 9:14||Q /Luke 10:7|
|Institution of Lord's Supper||1 Cor 11:23-26||Mark 14|
|command concerning prophets||1Cor 14:37||Synoptic|
|Apocalyptic saying||1 Thes. 4:15||21|
|Blessing of the Persecuted||Romans 12:14||Q/Luke 6:27|
|Not repaying evil with evil||Romans 12:17 and I Thes 5:15||Mark 12:12-17|
|Paying Taxes to authorities||Romans 13:7||Mark 9:42|
|No Stumbling Block||Romans 14:13||Mark 9:42|
|Nothing is unclean||Romans 14:14||Mark 7:15|
|Thief in the Night||1 Thes 5:2||Q/ Luke 12:39|
|Peace among yourselves||1 Thes||Mark 9:50|
|Have peace with Everyone||Romans 12:18||Mar 9:50|
|Do not judge||Romans 13: 10||Q /Luke 6:37|
These passages indicate that Paul knew versions off Jesus' teaching and Gospel stories two decades before Mark was written, What this means is the Gospel material was being transmitted in an era decades before the writing of Mark. This material also indicates oral tradition (as with the pericopes) we can assume this material goes back to era of the events themselves since we only abouit about 18 years between Crucifixion and Paul's early epistles
 Edgar J. Goodspeed, An Introduction to the New Testament, Chicago: University of Chicago Press, 1937
 "Pericope," Oxford Biblical Studies Online, Oxford University Press, 2016 online resource
http://www.oxfordbiblicalstudies.com/article/opr/t94/e1449 (accessed 10/14/16)
 Terence C. Mournet, Oral Tradition and Literary Dependency: Variability and Stability in the Synoptic Tradition and Q..Tubingen,Germany: Mohr Siebeck, 2005, 98.
Bloomsbury T&T Clark; 2nd prt. edition, March 1, 1992.
 Mahlon H. Smith, "Gospel of Thomas," Synoptic Gospels Pro,er 1997, online resource
http://virtualreligion.net/primer/thomas.html (accessed 10/14/16)
 Stevan L. Davies, The Gospel of Thomas: Annotated and Explained (Skylight Paths Pub 2002)
 Lisa Haygood, "The Battle To Authenticate 'The Gospel of Thomas'," LUX: A Journal of Transdisciplinary Writing and Research from Claremont Graduate University: Vol. 3: Iss. 1, Article 6. Available at: http://scholarship.claremont.edu/lux/vol3/iss1/6
http://scholarship.claremont.edu/cgi/viewcontent.cgi?article=1041&context=lux (accessed 10'/12/16)
 Stephen J. Patterson ,The Gospel of Thomas and Jesus, p. 18