Explanation:

'शैलोन्नत' (Shailonnat) can be broken down as 'शैल से उन्नत' (elevated by/from a mountain). This compound involves an implied case ending ('से'), which is characteristic of a Tatpurush Samas (तत्पुरुष समास). A Bahuvrihi Samas refers to a third entity. A Karmadharaya Samas involves an adjective-noun relationship. A Dwigu Samas has a numerical first term.