Frederic Edwin Church paints a vast, wilderness landscape and as the only student of Thomas Cole its unsurprising that many of Cole's themes/ideas are present in this piece.
The bowl like nature of the sky in Church's painting is a familiar one to the American landscape. Dense, red swaths of cloud convey the mood of the West. Maybe Church wanted to convey the pain, and suffering of Indian Wars and dispossession that came with westerly expansion. Another way to interpret the sky is to liken it to the United States flag. The red and the blue potentially referencing national friction and slave vs non-slave ideology as it was painted on the eve of civil war. The uncertainty of the sky conveys an intriguing mood and acts very much as the 'soul' of the landscape - an idea Cole professes in his 'An Essay on American Scenery' (1836).
The mountains are luscious and thick with green life which can be seen as a representation of the fertility and fruitfulness of America; though they are rather gloomy and imposing. They also frame the landscape in a grand way, like Cole suggests mountains of the American landscape do. Although they share the warm glow of the entire piece they are in fact mostly dark and unseen with reflects the threat of the American wilderness.
The water is still and tranquil, another of Cole's five essentials of the American landscape. In continuation - the body of water has that amber glow and gives a definite sense of presence. Church surely paints the landscape as though he wasn't alone. The trees in the foreground have a similar biblical reference; looking gnarled and burnt, potentially symbolising the 'burning bush' that Moses encounters in the book of Exodus. The trees also provide that harsh reality of the wilderness, especially the branch that juts out as a silhouette.
Finally the mountains in the background and the setting sun summarise the sublimity of the American west. They have an ethereal feel about them and the dazzling brightness forges a strong connection with God's presence and the wilderness. Both the mountains and sunset advocate Arthur Schopenhauer's ideas on the 'fullest feeling of sublime'. They give the audience, and probably Church as he painted it, the sense of smallness, overwhelmed by the insignificance of humans in the wild landscape of the West.