Find this map online: https://arcg.is/1iPymD

Link to one slide summary: https://docs.google.com/presentation/d/1DJ1M1RlPPY-HnrLzDv4JhLitdGxWWBfsNWwRno7Quvg/edit#slide=id.p

Introduction

The surface geology of an area is the type of geological material that are found above the bedrock, but beneath the soil. The geologic material that makes up the surface geology of an area help to determine the types of soil present in the area, and also how impervious the area is to water. 

Results

Most of the geologic surface of Madison borough is composed of Late Wisconsonian Glacial Delta Deposits, depicted in orange, which takes up about 1,010 acres of Madison’s 2,768 acres. This material was deposited by ice sheets during the most recent period of glaciation in America. The material is mostly weathered sediments carried from areas of higher elevation and a northerly direction. As the glacier expanded southward, it picked up sediments from the surface it crept past. When the glacier began to melt, the run off left behind many rocks, stones, boulders, and smaller material like sand and silt that make up the deposits. The second most common material that makes up the surface of Madison Borough is Late Wisconsonian Terminal Morraine Deposits, Rahway Till, depicted in purple, and that takes up about 709 acres. This material was left behind by the very terminus of the glacier; as it melted, geologic materials that had been gathered by the advancing of the glacier fell out of the ice and were deposited in this area, forming a ridge of sediments. For more information on the general surface geology of New Jersey, click here.

Importance of Surface Geology

Geologic surface deposits serve as the parent materials for soils, so the material present can have effects on soil type and health, and therefore land use, agricultural productivity, and permeability to water. Areas with soils that are less productive or less permeable may be less likely to be able to engage in agricultural activities, and may be more susceptible to flooding, especially with increased development. Additionally, soil type can limit what types of plants can grow in a certain area, and therefore can affect the type of agriculture that is possible or the type of forest present, such as the distinction between coniferous and deciduous forests in New Jersey. Forest cover is depicted in the map, outlined in green. 

Conclusion

The surface geology of Madison was greatly determined by ancient glacial activity which deposited sediments. These sediments serve as the base materials for soils, and therefore can affect the areas hydrology, agriculture, and development.

Data

Data was collected in collaboration with the USGS by the NJDEP. The data layer was created in July 2019 and was last updated on November 8, 2021. The data is displayed by color coded polygons that outline the areas covered by specific types of surface materials.