the stage to the fennian orogeny was set by a collision between keitele and karelia about 1920–1910 million years ago which resulted in a reorganization of the local plate tectonics. as concequence the bergslagen microcontinents collided with the keitele–karelia collage starting the fennian orogeny. the until then linear fennian orogen was "buckled" from 1870 million years ago onwards due to an orthogonal change in tectonic compressive stress. this resulted in various oroclines around the gulf of bothnia.