It has sediment, radiating asymmetrically southward from the mouth of the Astoria Canyon.
From Astoria Canyon's mouth, the fan extends about 100 kilometres (62 mi) to its western end, which is the Cascadia Channel.
The fan proper ends 160 kilometres (99 mi) south of the canyon mouth, although its depositional basin extends southward another 150 kilometres (93 mi) to the Blanco fracture zone.
[4] The fan extends about 100 kilometres (62 mi) to its western boundary, which is the Cascadia Channel.
Ash from the eruption of Mount Mazama has been found, in Astoria Fan.