In 1936, the
Sierra Club adapted a numerical system of classification. This system, without the decimals, was initially referred to as the "Sierra Club grading system." Class 1 was a hike, and higher classes were more difficult and technical, going up to class 6, which is referred to as
aid climbing. The fifth class began to be refined by climbers at
Tahquitz Peak in
Southern California in the 1950s. The first systematic presentation was in the 1956 edition of Wilts's guidebook for Tahquitz. Mark Powell is said to have exported the system to Yosemite around the same time. The standards for the fifth-class climbing grades as of 1979 were as follows: on
El Capitan in Yosemite,
free climbing a 5.13a route The original intention was that 5.9 would be the hardest possible free climb, with class 6 describing aid-climbing routes. Initially the scale was based on ten climbs at Tahquitz, and ranged from the "Trough" at 5.0, a relatively modest technical climb, to the "
Open Book" at 5.9, considered at the time the most difficult unaided climb humanly possible. In later years, as gear and athletic standards in the sport became more advanced, many aid routes were "freed" (i.e., climbed without aid), and the class 6 label fell into disuse, so that 5.x could be a label for any technical rock climb, regardless of whether most people were doing it free or aided. By the 1960s and 70s, increased athletic standards and improved equipment meant that class 5.9 climbs from the 1950s became only of moderate difficulty for some, while new 5.9 climbs were much harder. Class 5.9 began to be subdivided as 5.9- and 5.9+. Eventually, climbers began adding classes of 5.10 and 5.11 (rendering the "
Decimal" part of the Yosemite Decimal System name technically inaccurate). In the early 1970s, it was determined that the 5.11 climb was much harder than 5.10, leaving many climbs of varying difficulty bunched up at 5.10. To solve this, the scale has been further subdivided for 5.10 and above climbs with suffixes from "a" to "d". , only three climbs are considered to have a difficulty of 5.15d:
Silence, first climbed by
Adam Ondra on September 3rd, 2017., DNA, first climbed by
Sébastien Bouin on April 26nd, 2022, and B.I.G. first climbed by
Jakob Schubert, on September 20th, 2023. No climbs graded 5.15d have been repeated. == See also ==