Time for more nonsense from another Geo-toad;
What basalt clearly has in his possession is a sample of what is commonly referred to as 'rinded flint'. Whilst this terminology is not officially recognised in GS circles, it is in frequent use (for the die-hards it's commonplace in the CIRIA Digest 'Engineering in Chalk' as well as in use by the 'big boys' such as Arup, Mott McD and BBGE alongside BS:5930).
Where confusion occurs is when the flint undergoes colour changes when subjected to weathering processes. The dark grey to black flint is fresh, degrading to light grey to off-white when almost totally weathered. The rind of the flint (often referred to as the cortex or spall) is partially porous in comparison to the rest of the 'core', hence the rinding effect. That's not to say that the term chert is obsolete, in fact much the opposite! Chert is strictly the correct term, but flint had replaced it to encompass all of the weathered states and colours when derived from the chalk source rock; probably colloquially more than anything else.
It could be that your chalk was deposited glacially or fluvially having been eroded from the source rock (the southern states have a little chalk I understand), but not knowing your exact location I'd be hard pressed to take a stab. Here in the UK you'd be equally hard pressed due to the successive glaciations and denudation of the land mass into its current form. British Red is correct in what he says regarding its overall prevalence and occurrence; down in Hampshire, West Sussex, Kent, parts of Essex, Suffolk and Kent the Upper Chalk is overlain by 'Clay with flints' as the BGS so eloquently describe it. Essentially the chalk weathers to a reddish brown silty gravelly clay, from which the flints were removed and traditionally used to face masonry (especially churches and parish boundaries), provide ballast for vessels, provide flints for firearms and strikers as well as edges for cutting tools long before that.
All in all, even if it wasn't from an English ship, its still a resource worth having and something most avid Bushcrafters have in their fire kit alongside some amadou, charcloth and polypore. Happy firelighting