What makes Marrow of the Spirit by Agalloch notable?

'Marrow of the Spirit' received widespread critical acclaim upon its release, appearing on several year-end lists and helping to elevate Agalloch's status within the metal community. The album was praised for its ambitious length and intricate arrangements, influencing a wave of post-metal and atmospheric bands in subsequent years. When 'Marrow of the Spirit' was released in 2010, Agalloch was well-established within the atmospheric black metal scene, following their critically acclaimed album 'Ashes Against the Grain' from 2006. This album marked a continuation of their sonic exploration into nature-themed themes and complex compositions, solidifying their reputation as innovators in the genre.