In the LCMS's view, the Bible does not contain errors. The creation story is told as fact, rather than as an analogy. If we start with the Bible as inerrant, then what else can we believe than that God created the world in 6 days and rested on the 7th?
The LCMS accepts the possibility that the world may have been created mature. I believe the term "Young Earth" is a misnomer. A better term would be "Recent Creation".
Furthermore, Adam's sin not only changed man, but all of creation. The rules after sin entered the picture may not be consistent with the rules before sin entered the world.
I am a Creationiist and a Biblical fundamentalist; but that requires me to consider Genesis 1:1 - 2:2 through the lens of Psalm 90:4 “A thousand ages in your sight are like a single night when it is past” (as well as its citation in James).
What is the length of one “age”? I have no problem reconciling the records of fossil and rocks with the record of scripture so long as we do not insist upon 7 x 24 hour days according to our methods of measurement.