GEOLOGICAL AND HISTORICAL TALES OF THREE SUGARLOAFS IN MASSACHUSETTS, PENNSYLVANIA, AND MARYLAND

A common designation for isolated, mound-like promontories and mountains throughout the United States is “sugarloaf,” referring to the loaf-like shape into which sugar was once molded for shipment. In the NE, three such features are noteworthy, not only for their topographic eminence but also for their historical significance. All three sugarloafs have supplied their names to stratigraphic units.

Situated along the W bank of the Connecticut River in the Mesozoic Deerfield basin, MA, Mount Sugarloaf, elevation 652 ft, towers over the surrounding landscape, providing grand views to the E, S, and W. Gently E-dipping, Upper Triassic arkose—the Sugarloaf Arkose—forms steep cliffs overlooking the river to the E. 1 mi NW is the site of the “Bloody Brook Massacre,” where, on 18 September 1675, hundreds of Indians allied to the Wampanoag King Philip decimated a detachment of Massachusetts soldiers transporting corn down the valley from Pocumtuck (Deerfield), 4 mi to the N.

Sugarloaf Mountain, NE PA, is a synclinal, 1686 ft-high promontory that stands above the Conyngham Valley, 0.9 mi beyond the N edge of the Eastern Middle Anthracite field. Its capping ledges, long considered to belong to the Pennsylvanian Pottsville Fm., are now assigned to an informal conglomerate unit near the top of the Upper Mississippian Mauch Chunk Fm.—the Sugarloaf Mountain conglomerate. Because it overlooks the surrounding countryside for miles around, the mountain has given its name to the “Sugarloaf Massacre,” a Revolutionary-War skirmish which took place 2 mi to the E on 11 September 1780. There, at a spring in what is now Conyngham borough, American militia were surprised and routed by a band of Senecas and Tories.

Sugarloaf Mountain, MD, 1282 ft high, forms the core of the Sugarloaf Mountain anticlinorium in the Piedmont Province. It is underlain by the Lower Cambrian Sugarloaf Mountain Quartzite. The upper member of the formation, consisting of resistant white quartzite, forms rugged summit ledges that look out over the Potomac and Monocacy River valleys and Catoctin Mountain to the S and W. Sugarloaf Mountain figured prominently in local history: the nearby Monocacy Aqueduct on the Chesapeake and Ohio Canal was constructed of quartzite from there in 1829-33, and the mountain summit provided a station for the Union Signal Corps throughout the Civil War.