This map shows the buried drainage pattern in the Niagara Peninsula as Dr. Spenser saw it as the result of his work in 1907. Present knowledge sees this drainage system in different light as reported by Flint and Loccam in Buried ancestral drainage between lake Erie and Ontario. "Over the past few decades, extensive data have become available and detailed bedrock surveys of areas within the Niagara Peninsula have been published. To date, however, no overall re-evaluation of the buried bedrock topography has been undertaken...Upstream from Niagara falls to lake Erie, the location of the St. David's drainage system remains unknown. However, more information collected, we assume it is unlikely that the channel carried a river which flowed in an opposite direction to the present Niagara River, but rather that it was a tributary of the Erigan for a relatively short geological time, before another channel was opened to drain Lake Erie. The St. David's channel may represent the only period, other than the present, when the great lakes emptied through the Niagara Peninsula.