2: Logan River assignment

Total elevation change: Max (8,095 ft) - min (4,408 ft) = 3,687 ft (1.1 km)

Base-level control of the Logan River today 

Base level is the level to which a channel naturally cuts.  Dams and geology control base-level today. The main base level feature currently is Cutler Reservoir at 4,414 ft.

Base level control of the Logan River 18,000 yrs ago

18,000 yrs ago Lake Bonneville was around the level of the Shoreline (~4,850ft), so this lake elevation would be a strong base level control at that point in time.

Mainstem Length: 54 miles (86 km)

Concavity

Concavity = 2A/H

  = 2(350 m) / 1,100 m

    = 0.6

Knickpoints and hypotheses about controls

There is a knickpoint between miles 45 and 47 that coincides with an unnamed spring entering the River in the upper watershed. Perhaps there is stronger bedrock here so less downcutting. 

There is a knickpoint between miles 22 and 20, coinciding with third dam, and second dam, affecting normal river downcutting. Dams first slow, but then accelerate downcutting downstream.

There is also possibly another knickpoint at the mouth of the canyon, coinciding with first dam, although this is hard to tell because of the transition from confined to unconfined valley.