Burlington's subsurface is not uniform. The city stretches from the Lake Ontario shoreline north across the Iroquois Plain, climbing through the shale and dolostone of the Niagara Escarpment, a landform that dominates local construction. Overburden here often consists of Halton Till—a dense, stony, silty clay diamict—overlying fractured Queenston Shale. Depth to bedrock can shift from less than 1.5 m near the escarpment brow to over 20 m in buried valleys south of the QEW. An exploratory test pit program, executed under ASTM D2488, lets us directly observe this transition. When we open a pit, we are not just logging soil; we are mapping the interface between glacial drift and weathered rock, a boundary that controls footing design and groundwater movement. In our experience, combining a test pit campaign with a targeted grain size analysis helps quantify the till matrix, while slope stability assessment becomes essential for any cut deeper than 2 m on escarpment properties.
Direct observation of the till-shale contact in a test pit provides more certainty for bearing capacity decisions than any number of borehole logs alone.
