[2] Troubled by illness throughout his life, Sederholm originally chose to study geology to allow him to work outdoors.

Working on local Precambrian basement rocks, Sederholm instigated a map-making programme that, between 1899 and 1925, published many maps and descriptions of their geological history.

Sederholm termed these as migmatites, and viewed them as the product of the intrusion of igneous magma into metamorphic rocks at depth.

Aside from his geological work, Sederholm was a member of the Diet of Finland, and undertook missions from this to the League of Nations.

In the 1974 historical novel Centennial, James Michener listed Sederholm among those scientists who made early estimates of the age of the Earth.