Niall,
I am no expert on the "typical CBM Biarritz" but was more commenting on the inspiration for the original concept. As far the original concept goes, the swale or the dip was before the green, between the first plateau (the "hog's back") and the plateaued green. I am not sure who came up with the idea that that dip or swale represented the chasm, but I don't think it was CBM.
Some Biarritz holes play over a "chasm" or water prior to the first plateau (Yale for example) but there is no mention of a chasm in the original description, where the swale was before the green, between the first plateau (hog's back) and the green. The first few Biarritz holes (Piping Rock and Sleepy Hollow) did not have any sort of chasm carry prior to the first hog back plateau. (Arguably the first hole influenced by CBM's Biarritz concept was Merion's 17th and it did have a chasm/quarry, but that is another discussion.)
Interestingly, in addition to his Biarritz hole at Sleepy Hollow, CBM also built a green with a perpendicular swale bisecting the green much like many think of as a biarritz green. But it was on a longer hole, 400 yards. The hole apparently had a road bisecting it at about the midway point. Given the green with the swale in the middle, does it bring to mind Hutchinson's description of the 16th at North Berwick and the "burn which often punishes a good drive?"
Anyway, this green-with-a-perpendicular-swale at Sleepy Hollow was in addition to a Biarritz par three (with a swale before the green) and another double plateau green. (Same thing at Merion --a double plateau, another double plateau with the swale perpendicular to the line of play, and a long par three with at least some biarritz characteristics.)
So it seems there may have been at least three separate two concepts originally.
1. A double plateau green.
2. Another double plateau green but with the swale perpendicular to the line of play, bisecting
the green. (What some today would call a Biarritz type green.)
3. A long par three with a hog back plateau, then large dip or a swale
short of the green, then a plateau green. (The original Biarritz concept.)
I guess we could throw in a fourth concept which involves a shot over a gaping chasm, but while the Chasm at Le Phare was probably among the more visually stunning "chasms" this was hardly a unique concept.
The other interesting thing is the HJW quote from 1913 where he refers to a Biarritz hole which is new to the US (presumably) which kind of suggests to me that this new hole was a variation of an earlier "Biarritz" design already introduced to the US, or are am I missing something ?
Interesting take on that. As I said, CBM had first discussed the hole concept in 1906 (at least that is the first reference I have found) but I think that first one he
built was at Piping Rock. That said, while CBM and HJW didn't build Merion, they were heavily involved during
the design stage, and Merion's 17th has some characteristics consistent with the early Biarritz concept. While they are contemporaries, Piping Rock opened after Merion East.
[Believe me, I am NOT trying to start another fight about Merion. Just trying to fill in what I know about the evolution of the Biarritz concept, and given CBM's involvement at Merion shortly after NGLA, it is an extremely important course in the chronology.]