AN INTRODUCTION TO THE NEW ENGLAND TOP OF ROCK (NE TOR) PROJECT

The top of bedrock is recognized as an important 3D surface in geology, hydrology, hydrogeology, geomorphology, soil science, and engineering; however, it is very poorly known where it is buried. Prior to the advent of LiDAR, even the top of rock at and near the land surface was difficult to map accurately in forested regions like New England. A modern high-resolution database of the bedrock surface altitude is lacking. The primary goal of NE TOR is to develop an inventory of available data and establish a plan for creating a model of the bedrock-surface altitude in New England. The objectives include creating a seamless GIS database for the altitude of the top of bedrock beneath the unconsolidated glacial deposits, mapping the 2D boundary between exposed bedrock and surficial deposits regionwide, and designing a robust spatial database for 3D modeling. Long term objectives include developing 3D models and depictions of the thickness of surficial deposits. This work will be coordinated directly with the New England State Geological Surveys and complement their efforts to establish a New England Coalition of State Geological Surveys.

This presentation serves as a progress report on the initial task of assembling an inventory of available data and assessing the viability of that data at various scales. Key data sets in New England include: 1) Surficial geology, 2) borehole databases showing depth to bedrock, and 3) altitude of land surface (LiDAR & 10 M DEMs). Subsurface geophysical data sets will also be evaluated, although the distribution and extent of these may be limited. Surficial geologic maps exist at various scales and complexity for most of New England. The horizontal-to-vertical spectral ratio (HVSR) seismic method can be used to fill data gaps and test models in crucial areas.