By: magic-gigapans
Image: Chris Johnson, Mid-Atlantic Geo-Image Collection
License: Creative Commons Non Commercial ⧉

Uploaded: 13 May 2020
Last Updated: 15 May 2020

1.37 gigapixels
52,140 x 26,312 pixels
173.8 in X 87.7 in at 300dpi
207 pixels per inch

Leesburg Member of the Balls Bluff Siltstone also known as the Leesburg Conglomerate. This is a Triassic Basin sediment found along to the east of the Blue Ridge Anticlinorium. It is part of the Newark Supergroup. It contains limestone clasts likely originating from the Tomstown Formation and the Frederick Limestone. It is poorly sorted with clasts ranging in size from .5 cm to boulders as much as .5 m in diameter. The clasts are sub-rounded to sub-angular. These attributes along with the very unstable lithic clasts suggest that the formation is located close to its sediment source. Proximity to its source, age, and regional patterns seen in geologic mapping of the region suggest that the Leesburg Member was deposited as alluvial fan deposits and/or debris flows from the west into a failed rift basin during the rifting of Pangaea. A hypothesis explaining the origin of the sediment is that shed from the Blue Ridge Anticlinorium (From formations up-section, which have by now been completely eroded away from the stratigraphic record preserved in the eastern and western limbs of the Blue Ridge Anticlinorium) which was uplifted during the Alleghenian Orogeny some 280 million years ago. The GigaPan was taken looking roughly south meaning that the bedding is dipping to the west which is consistent with the trend in the area.