From what I understand of the history, Yosemite Decimal System (YDS) grades came about when class 5 in the preexisting system was subdivided into 5.0 through 5.9. This was done by Chuck Wilts, Royal Robbins, and Don Wilson, who were members of the Rock Climbing Section of the Angeles Chapter of the Sierra Club, as part of Wilts's 1956 guidebook to the Tahquitz Rock area. A particular climb served as the original definition of each decimal point. Wikipedia states that The Trough was the original definition of 5.0, while Open Book defined 5.9. What was the list of ten climbs that defined these grades, and what grades are they considered to be?

Related: Please Explain Rock Climbing Grades


Below is the list that I found by googling on "chuck wilts" 1956 tahquitz yds. After the name of each route is the consensus rating on mountainproject.com. Each climb is hyperlinked to a description on mountainproject.

5.0 - The trough, FA 1936 (.4)

5.1 - Fingertip traverse, FA 1936 (.4)

5.2 - Frightful variation of the trough, FA 1944 (.2)

5.3 - East lark, FA 1950 (.5)

5.4 - Angel's fright, FA 1936 (.6)

5.5 - Ski Tracks (left .6, right .9), FA 1947, 1957

5.6 - Sahara terror (.7), FA 1942

5.7 - Fingertrip (.7), FA 1946

5.8 - Mechanic's route (.8 R), FA 1937

5.9 - Open book (.9), FFA 1952 (aided previously)

  • Grade inflation in action, lol
    – user3522
    Aug 17 '15 at 22:09
  • @bchilders: I think the FA of Mechanic's route in 1937, with a hemp rope, is particularly impressive. Interestingly, there seems to be very little inflation at the top end of the scale, mainly at the bottom. But many indoor climbing grades do seem to have a ton of inflation at the top.
    – user2169
    Aug 17 '15 at 22:40
  • 1
    Yeah, IIRC, there was a R&I article on hemp rope classics that was really impressive. I find route grading in general quite interesting - I read a blog post once, which tried to quantify grades based on the number of ascents famous or popular routes had, and found a geometric curve leading to La Dura Dura, concluding that each letter grade is something like 1.7x as hard as the one below it. Wish I could find the article...
    – user3522
    Aug 18 '15 at 14:40

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