GIScience has only rarely dealt with linguistic data so far despite its challenging nature with many peculiarities that make analysing spatial language variation a worthwhile endeavour. The two commonly used paradigms in dialectology to deal with dialectal areas in space, the dialect continuum and isoglosses, respectively, correspond to the dichotomy of fields vs. entities found in GIScience. These two ways of conceptualising boundaries in dialectal space engrain the problems that the quantitative analysis of delineations of language areas is facing. We present initial steps of a project that aims at quantitatively modelling language area formation and the influences of geographic factors on boundaries in dialect continua. We start by analysing the distinctive features of language data that set them apart from other types of data commonly dealt with in GIScience. We then phrase the key questions that guide the analysis of such boundaries, and we propose a range of GIScience methods that can be used to answer these questions. We also present preliminary results of applying some of the proposed methods on Swiss German syntax data.