Jim,
You may be right about the first light colored swath, but it looks like a bunker to me. My assumption was that the up slope of the hog's back approach is the shiny half circle just beyond what I thought was a bunker. Whigham's description describes the feature deflecting balls to the sides, so it must have had some sort of knoll or bump to do this. Either way, this doesn't look like anything I want to try to run the ball across.
I too have been trying to make sense of his description of the role of the hog’s back-then-30 yard dip-then green as well as Macdonald’s earlier description of hog’s back-then 80 yard dip-then-green. Surely CBM wasn’t contemplating running the ball 80 yards onto the green? Although I would probably try the shot, it seems a bit much, and if this was the “chasm” hole that doesn’t leave much room for the fearsome “chasm” even if the hole was 210 yards. Turns out Scotland’s gift contains a typo. The snippet from Outing is below; 30 yards between the hog’s back and the green, not 80 yards.
But CBM did describe it as a “sharp hog back” and when this description is considered with Whigham's description and the Lido plasticine, it is pretty clear that initially they were contemplating some sort of hog’s back (or bump or hill) which would deflect rolling or bouncing balls not hit perfectly true. I agree that this would make landing it on or short of the sharp hog’s back a rather unappealing option, and that on this hole the better play would be to carry to the down slope of the dip/valley/swale and let it run from there. But given that the dip was 30 yards, there would have been ample room to do this without hitting into the upslope.
As for why they never built such a “sharp hog back” it is difficult to say, but here are a few things to consider:
2. They did build the Lido, and the feature shown on the plasticine would reject balls as Whigham anticipated, and it did contain more room to land the ball on the downslope and run it up.
1. As you said, this would make the shot extremely demanding, especially with a wood, so perhaps they figured it was too demanding on shorter hitters and cut off the top of the hog's back to make a plateau.
2. Contrary to popular belief, for the most part CBM worked with what the site gave him (thus no Biarritz at NGLA.) And it may be that the early sites did not have such a feature to incorporate into the hole, and so he did without, realizing that the hole was plenty demanding anyway.
3. The landing area as a plateau still serves the purpose although to a lesser degree, if one misses is well off line the ball will roll down the steep sides of the plateau and into trouble.
4. Given that the full green valley/dip/swale, and hog's back would have been a monumental undertaking to create, it may have been more practical to compress things a bit, makin the swale more abrupt and less far across. But without ample room to land the ball on the downslope on the short side of the dip/swale/valley, the hog's back would have made the hole nearly impossible for the run-up, and a more forgiving approach would have been necessary.
5. All of CBM’s Biarritz holes were built by Raynor, and CBM had little or nothing to do with many of the holes we consider Biarritz holes. Raynor had never been to Biarritz that I know of, and the plateau may have been his take on the concept. (That is why I find the Lido plasticine model so compelling; it shows what CBM planned to do, whether it was perfectly carried out or not.
Not laying down the law here, just throwing out a few ideas of what might have happened, and keeping in mind the playability concerns.
Jim and Mac and anyone else, did anyone notice that two days ago TEPaul was arguing that the Valley of Sin short of Merion's 17th was the inspiration for all future Biarritz swales to come, yet now has concluded that Merion's hole has nothing to do with the Biarritz concept hole type or concept? I just wanted to point it out for your consideration.