We have discussed two of the three major topographic divisions of the
park—the high mesas and the benchlands—and there remains to consider the
third division—the canyons of the mighty Green and Colorado Rivers and
some of their tributaries. After we discuss a few features common to
both rivers, we will take up the details of each river.
A glance at the map (fig. 1) shows that above the confluence both rivers
are very crooked and contain many loops, or meanders, the most striking
of which are Bowknot Bend of the Green River (fig. 62), several miles
north of the park, and The Loop of the Colorado River (fig. 74). In
contrast, the main stem of the Colorado River below the confluence is
considerably straighter. Not apparent on the map are the facts that the
crooked rivers above the confluence have very gentle grades and are free
from rapids or falls, whereas a few miles south of the confluence the
main stem plunges into Cataract Canyon—the steepest and wildest reach of
the river, containing 64 rapids. These differences are partly explicable
on the basis of the geologic structure and character of the rocks
through which the rivers have cut. Above the confluence, the soft strata
dip gently northward, so in flowing generally southward the two rivers
are cutting “against the grain,” which tends to impede their flow and
thus reduce their grades. Below the confluence, the hard limestones of
the Hermosa Formation lie relatively flat for several miles and then
begin to dip gently southward, thus allowing the river to cut “with the
grain” and therefore drop more rapidly.
The quiet, smooth waters above the confluence permit power boating
between the towns of Green River, Utah, and Moab during part of the
year, whereas the rapids below Spanish Bottom, 3½ miles below the
confluence, restrict river travel to float trips using sturdy boats or
rafts.
Above the confluence, a so-called Friendship Cruise is run each year
during the Memorial Day weekend. Participants tow their own power boats
on trailers to the town of Green River, and after the boats are
launched, facilities are available at nominal cost for transporting cars
and boat trailers to Moab to await the arrival of the boats. Although
some high-powered speedboats are reported to have made the run down the
Green River to the confluence then up the Colorado River to Moab in a
few hours, the trip for most boats requires 2 to 7 days.
Trips by power boats, including jet boats, can be arranged from either
Green River or Moab. Some passengers from Moab return by jeep from
Lathrop Canyon via the White Rim Trail, and some from Green River return
on land via the Horsethief Trail. Many prefer the quieter float trip
down to the confluence, with return to either town by a prescheduled
power boat, and some more adventurous souls float through the rapids of
Cataract Canyon all the way to Lake Powell.
In the spring of 1972, a 93-foot 150-passenger stern-wheeler (fig. 69)
began passenger service on the Colorado River from just above Potash to
the foot of Dead Horse Point and return (Lansford, 1972).