The family of R-trees is suitable for storing various kinds of multidimensional objects and is considered an excellent choice for indexing a spatial database. Region Quadtrees are suitable for storing 2-dimensional regional data and their linear variant is used in many Geographical Information Systems for this purpose. In this report, we present five algorithms suitable for processing join queries between these two successful, although very different, access methods. Two of the algorithms are based on heuristics that aim at minimizing I/O cost with a limited amount of main memory. We also present the results of experiments performed with real data that compare the I/O performance of these algorithms.