The paper investigates the use of PPs, specifically prepositions and the case marking on their DP arguments, in moribund North American (heritage) Icelandic (NAmIce), using data from a map task experiment. Since prepositional phrases combine semantic properties with morpho-syntactic properties, PPs allow us to investigate the relative vulnerability of both domains at once. Our results show that while the prepositional inventory of NAmIce is not reduced as compared to Modern Icelandic, the choice of prepositions is subject to crosslinguistic influence from the dominant language English. For case, we find an increase in the use of nominative and accusative case at the expense of the dative; prepositions may take over case functions too. Our results are in line with previous research on case in heritage languages as well as studies on language change, while partially contradicting the assumption that loss is reversely related to acquisition.
