Geology

The character, physical features, and development history of Patterson Park were strongly influenced by the geology of the site. Part of the Coastal Physiographic Region, the underlying rock was formed from the deposits of a historic flood plain and swamp that existed in a previous geologic era when the site was completely under water. The entire site is part of the Arundel Geologic Formation and most of the park is part of the clay facies which are predominantly clay deposits. However, the high point, historically known as Hampstead Hill, the Rodgers’ Bastion, and currently the site of the Pagoda, is underlain by a sand facies. This structure has played a major role in the park’s history and evolution.

The sand facies can be envisioned as a knoll of sand deposits that overlies the clay facies. This sand formation was likely deposited as the result of a major flood that transported the sand from uplands and deposited it in the swamp area. The same type of sand formation exists beneath Highlandtown, another high point in the region. These sand deposits and resulting soils are more resistant to erosion than the surrounding clay, making the people of southeast Baltimore graced with a compelling high point at the Pagoda, with a view that has attracted people to the site since at least the 18th century. The popularity of this high point in the early nineteenth century may indeed have spurred William Patterson to consider donating his first six acres to the City of Baltimore.