Dickie Hall, of Waitsfield, VT, was inducted into the Vermont Ski and Snowboard Hall of Fame in 2017. I am taking the following from his induction video available here. These are just the high points. It's definitely worth watching the video for filling in the details.
In the early 70s he left his job, as a
patroller, at Killington, (one source quotes him saying that he had
been fired) to go work at the Nordic center nearby, which was looking
for instructors. It was his first exposure to cross-country skiing.
The equipment gave him a freedom to explore new places that he had
never before experienced on his skis.
His downhill skiing background, coupled
with the discovery of the Telemark turn in an old instruction book,
prompted him to take up using his cross-country skis, which he
describes in the video as being like “wooden arrows,” with boots
that were like “rental bowling shoes,” to link turns skiing
downhill. To practice his turns he started going to groomed slopes,
taking others along.
He began experimenting with the use of
Alpine skis mounted with three-pin bindings. He was turned away from
riding the lift in his Nordic gear by ski areas like Stowe, but found
a home at Mad River Glen.
As a PSIA ski instructor he asked the
Association for permission to instruct in the use of the turn. He was
denied, being told it was a downhill turn by the Nordic branch and
then, that it was a Nordic turn by the downhill branch. He quit and
started NATO, the North American Telemark Organization.
Tens of thousands of people became
introduced to the use of the turn through his festivals, clinics and
camps. The ski manufacturers took note and more Alpine-like Telemark
equipment became available. As it gained popularity, the reluctance
of ski areas to allow use of the equipment disappeared. As people
gained proficiency in using Nordic gear on traditional Alpine
terrain, interest in backcountry downhill skiing started to grow.
Cross-country skiing wasn't just ski du fond, valley skiing, any
more.