The St. Lawrence Island dialect of Siberian Yupik uses a mixture of prepositional cases, demonstrative pronouns and adverbs and positonal stems.
Cases
The SLIdoSY has several cases of which four can be used to convey information that English would convey via prepositions:
Localis, which is used for the place the action or state described by the verb occurs and objects of camparison in certain cases.
Terminalis, which is used for the destination of a directed action and some mumbo-jumbo with embedded verbs that I don't fully understand.
Vialis, which is used for the route of physical or temporal motion, the mean by which something is done, and a part of a whole towards which action is directed.
The ablative-modalis case which is used for a whole lot of things:
1. The indefinite object of an intransitive verb
2. The point of physical or temporal origin
3. Further information about nouns expanded with verbalising suffixes
4. The subject matter of speaking, thinking, etc.
5. Indirect objects of ditransitive verbs
6. Objects of camparison
7. The instrument used to perform an action
Obviously, not all the functions of the different cases replace prepositions, but some of them do. Examples:
Neghtuq angyamini. "(S)he/it ate in his/her/its own boat". Angyamini being composed of the stem angyagh ("boat") and the localis, singular number, 3. person reflective posessor noun ending "-mini"
Kiiwegnekun esnightunga. "I walked along the river." Kiiwe-gnekun is composed of the stem meaning river and -gnekun which is the vialis, dual nuber, unposessed noun ending. (Rivers, for some reason, are dual, even if there is only one river)
Demonstrative pronouns and adverbs
Unlike English where this and that are the only demonstrative pronouns and here and there are the only demonstrative adverbs the SLIdoSY has a large number of such words. These are made from special demonstrative stems expanded with a variety of suffixes. A few examples could be the stem "kiwe" which meas "towards southeast" (if you are in the town of Gambell it also means "towards Savoonga" (the other town on the island)), and the stem "qage" meaning outside.
These stems are then inflected with different endings to elaborate the meaning.
If one wishes to indicate the nuber of objects and which case the objects are in one can in most cases use by using the ending "u" in singular and "ku" in dual and plural followed the unposessed nound endings. Examples:
Kiwe + u + mi (singular localis) = kiwumi "In the one towards southeast (or towards Savoonga)"
Qage + ku + gneng (dual ablative-modalis) = qaagugneng "From the two outside"
Demonstrative adverbs uses the suffix "-a", as well as a seperate set of case endings. Example:
Age (over there) + a + gun (vialis) = agagun "Through the area over there.
The difference between demonstrative adverbs and demonstrative pronouns are that adverbs refer to areas, while pronouns refers to entities. Compare:
Adverb: Esghagaqa qawaak pikani. "I saw a bird up there"
Pronoun: Esghaghaqa qawaak pikumi. "I saw a bird in/on the thing up there.
Positional stems
The SLIdoSY has a number of stems that refers to relative positions. Examples of such stems are asi "area beneath" and sivu "area in front". These can the be conjugated using the usual noun endings. These stems are used as posessions to indicate relative locations. Example:
Sivu + mni (localis, singular, 1st person singular posessor) = sivumni "in front of me" (lit. my area in front)
Additonally the suffix "-ate" can be added to a demonstrative to form a positional stem. This shifts the frame of reference from the speaker to the grammatical posessor.