“We know that ‘day’, while generally 24 hours, refers to the time it takes sun to return to the same apparent position in the sky; this is supported by Joshua’s “long day” (Josh 10) being referred to as a ‘day’. (So, one must accept that ‘day’ needn’t refer to a 24 hour period.)”
What the scripture actually says:
Jos 10:13 And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies. Is not this written in the book of Jasher? So the sun stood still in the midst of heaven, and hasted not to go down about a whole day.
The last part of the verse actually indicates that this day WAS a 24 hour day and not, as you suggest, that a day could be more than a 24 hour period.
The use of the Hebrew word “yom” used in scripture indicates the same period of time in virtually every instance it is referenced. Perhaps the question folks need to be asking is what was time like before sin entered the world. What was creation like before sin entered the world. Sin is a terrible thing, don’t you know:
Rom. 5:12 Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned:
Rom. 8:21-22 Because the creature itself also shall be delivered from the bondage of corruption into the glorious liberty of the children of God. For we know that the whole creation groaneth and travaileth in pain together until now.
Sin brings forth death, decay, corruption. What science is doing today is measuring that which is subject to these forces. What God made by His original design was not. And I’m willing to bet that science has no way of measuring/accounting for the variable “sin” in its calculations, yet this is THE factor, biblically speaking, when it comes to understanding what brings forth the death of something.
It clearly says that the sun stood still "about a whole day" -- if a 'day' is 24 hours and that's how long it stood still how can you say that Joshua's 'day' was 24 hours? (24 + about 24 = 24?)
It's really not that hard — my point is that this "about 48"* hour day is still clearly referred to as a 'day' even though it is clearly unlike other days. The point is that the reference for 'day' is not 24-hours, but the time it takes the sun to complete it's circuit in the sky. If there is no sun, nor [solid] Earth from which to reference the non-existent sun for those first days then why should they be 24 hours? These creative days are also unlike other days, especially those where the sun [or Earth-proper] didn't exist.
I'm not saying that they aren't 24 hour days, but I am saying that they needn't be.
IOW, the truthfulness of the creation account does not rest on the most restrictive usage of the words — indeed, your claim that "almost all" instances of yom are 24-hour days implicitly admits that some appearances of yom do not — the Bible isn't about describing the universe with scientific precision to people, it's about showing us who God is and why we need Him — in short, it is about Jesus.
A quick search reveals this article which claims the only appearance of yom in the old testament with the evening and morning association is in Daniel 8 and refers to a set of years.
Outside Genesis 1, yom occurs only 4 times in combination with both Hebrew words for "evening" and "morning." The actual word order of "evening" followed by "morning" in combination with yom (as seen in Genesis 1) occurs only once outside Genesis 1. It is ironic that this one verse comes from Daniel 8:26, which defines yom as a period of time at least 3000 years long:"The vision of the evenings [ereb] and mornings [boqer] Which has been told is true; But keep the vision secret, For it pertains to many days [yom] in the future." (Daniel 8:26)Obviously, the claim that "All 61 times the text refers to an ordinary day-why would Genesis 1 be the exception" is false, just from this verse - the only verse that perfectly matches the usage found in Genesis 1.