Geology of Katmai National Park & Preserve

Katmai National Park & Preserve, or more precisely the Aleutian Range which is within the Katmai National Park & Preserve is a portion of the Ring of Fire – nothing to do with Johnny Cash – this Ring of Fire is in the Pacific and is one of the most active volcanic belts on earth. The Aleutians grew as a direct consequence of the movement between the American and the Pacific plates. The whole of the Katmai region trends in a northeast / southwesterly direction along the Aleutian Range, dipping slightly towards the southeast. Katmai National Park & Preserve is bisected by the Bruin Bay Fault, the northwestern side of the fault displaying rocks from the Jurassic and Tertiary periods and the southeastern side of the fault being relatively flat lying sandstone. This is a very geologically complex area indeed.

Katmai National Park & Preserve has four very distinct regions;

the Aleutian Range
the lake country
the coast
the lowlands of Bristol Bay

All of these regions have been influenced topographically by glaciation, well, we are talking about Alaska you know. Glaciers created the u-shaped valleys with deep lake basins, dumping the eroded materials which was carried along by the mighty advances of the ice. The volcanic mountain range of the Aleutians rise more than 7,000 feet above the Shelikof Strait. Rivers from the highlands drain into the large deep depressions amid the low rolling hills of the lake country. We’re talking about lakes like Naknek, Kulik, Coville and Nonvianuk. These rivers then flow on into the Naknek or the Alagnak rivers and spill out into the Bristol Bay lowlands.

Okay, it’s a bit irritating to start with and it sure takes a lot of getting going, but it’s pretty good once you get past all of that stuff.