The hypothesis that the Oak Ridges Moraine (ORM) formed between two converging (roughly NS) ice streams is tested based on critical, available field data. These data (e.g., DEMs,
geological mapping, high-resolution reflection seismic profiles, continuous core, and, analysis of sediment type, architecture, and paleoflow data) refute the converging ice stream hypothesis for deposition of the ORM. Streamlined landforms, used to
re-construct ice stream flow paths, go beneath ORM as shown by surface mapping, seismic profiles and cored boreholes; hence, the streamlining event is older than ORM and has no direct bearing on its formation. Meltwater channels that truncate the
streamlined landforms are part of the ORM ice stream hypothesis, and they are inferred to represent (sub-aerial) spillways that end at the north side of ORM. These NS meltwater channels are also shown to extend beneath ORM; they have eskers on their
floors, and thus, are subglacial not sub-aerial channels. Halton Till, the inferred southern, ice-stream bed, is not present in the predicted ice stream areas. Halton Till overlies ORM sediment; thus, Halton can not represent an ice-stream event that
formed ORM. Halton sediment, in addition, occurs in transition from ORM glaciofluvial sediment, and, comprises interbedded diamicton and glaciolacustrine sediment, not the predicted ice-stream, deforming-bed sediment facies. ORM glaciofluvial to
glaciolacustrine sequences have a clear east to west paleoflow, in conflict with the expected ~NS sediment flux from the converging-ice-stream hypothesis. The failure of the ice stream hypothesis to explain field data in the area and formation of
ORM as predicted, casts doubt on applying this process model in the ORM area, and, in adjacent areas of southern Ontario.