Last question first:

3) Cascades at the Homestead is mostly a Flynn design. Back in the 1970s, Robert Trent Jones ruined the 14th and 15th holes, but the rest of it is all Flynn. It's one of his greatest courses. But Cascades is a mountain course and therefore plays NOTHING like Shinnecock and NOTHING like a parkland Flynn course such as Lancaster.

Merion is only partially a Flynn course. It was designed by Hugh Wilson in 1912. In about 1925, Flynn played a part in building five new holes. Wilson's old 10th and 12th holes originally crossed Ardmore Avenue, which was a country road in Wilson's time. Holes 10 thru 13 had to be re-routed to avoid the road, and this necessitated a shifting of the old 1st hole as well. It was this re-aligned Merion which Bobby Jones played during the 1930 Grand Slam.

The Country Club (Brookline, MA) is another partial Flynn design -- very partial. The original 18 was laid out by Alex Campbell prior to the turn of the century. That was the course on which Francis Ouimet won the famous 1913 US Open. All 18 holes of that course still exist, in pretty much their same form. In 1927 Flynn was called in to build an additional nine holes on outlying land which was called the Primrose nine (the old two nines were then named Clyde and Squirrel). When TCC got the 1963 Open, a composite course was used which deleted several old Clyde/Squirrel holes in favor of some holes from Flynn's Primrose nine. The Flynn holes in a US Open setup would be the modern 11th, 12th, and 13th. The rest of the place really does date from Ouimet's day, albeit with a few retouches by Rees Jones for the 1988 Open.

To me Lancaster CC is the archetypal Flynn course, and that's no accident -- he tinkered with that place for 20 years, with his last additions being in 1941. It is 100 percent Flynn and hosted a lovely 2015 Women's Open.

Though Shinnecock is the greatest course Flynn ever did, it plays nothing like any of the above due to its maritime setting. The closest Flynn course you'd get to that is the old Atlantic City CC, but the land there is banal in comparison.

2) Shinnecock is built entirely on sandy sub-soil which drains perfectly for golf. Such soils require NO alteration to build greens, so what you see are Flynn's original 1931 greens. Cut them short and they'll dry out in a flash.

When you think about "replacing" or "doctoring" sub-soils, you're speaking of the typical INLAND course we are all used to built on clay which does not drain. These courses require special greens mix and drainage.

3) Flynn's 1931 masterpiece is the third iteration of a golf course at Shinnecock. The first was done by Willie Dunn in the 1890s and hosted Shinnecock's first Open in 1896 (they were a USGA founding member). That course was completely replaced by Charles Blair Macdonald (who also built the National right next door) in 1917. When New York State road building killed that course, the club bought some new land to the north for Flynn to build on. Flynn used some of the land of Macdonald's old course, and in fact he retained two Macdonald holes in his design (today's 3rd and 7th). The Macdonald holes are still pretty much as constructed in 1917.