On 2009-12-18 00:09:50 -0800, Steve Slatcher > said:

>>
>> By seam[1] I mean the same level of limestone as it was deposited.
>> After deposition, the seam distorted. It now dips under the English
>> Channel, and it breaks through to the surface in Champagne and Southern
>> England to form the South Downs. It will not be identical rock, as it
>> is obviously in 2 different places, but it was laid down at the same
>> time and by more or less the same process.
>>
>> As for support, you will find quite a few references to it being
>> (nearly) the same rock on the Web. I recently saw a section diagram
>> showing the limestone layer as I described it above, but unfortunately
>> I cannot remember where. I must admit I have not examined the
>> geological basis for the claim, but I see no reason to doubt it.
>>
>> I know "seam" is used for coal, but maybe I misused it in applying to
>> limestone.
>
> Er, sorry. I meant chalk of course, not limestone. And the geological
> term for my "dip" is syncline. And "seam" is stratum, or layer. That's
> what comes from posting as soon as you wake up!

Thanks.... Amazing what you can learn on this chat. I asked about
"seam" as here in the far western US, "seam" tended to be used for a
dike or some formation which ran across layers of laid rock - as in a
seam of gold ore...