Howell Caves, Washington County
Five openings and solutional pockets are developed in the limestone cliffs near McMahons Mill (formerly Charles Mill or Cedar Grove Mill) along the Chesapeake and Ohio Canal. All five caves occur in the Tomstown Dolomite (dip 25º E., strike N.-S.).
The area itself is almost entirely surrounded by metamorphic or igneous rock bodies Catoctin Metabasalt to the south and west, Antietam Quartzite to the east, and a localized marble to the north, with faulting along the metabasalt contact. The caves are drained by Little Antietam Creek. The major portions of the caves are developed along strike joints, with bedding exerting an influence on passage shape and speleothem occurrence. The general dip is 25º to the east away from the upthrown fault block of the metabasalt to the west.
The entrance to Howell Cave, at the base of a cliff, is a low, gravel-floored crawlway which extends for twelve feet to connect with a room approximately 18 feet in diameter and ten feet high. A muddy crawlway leads to a second room which is ten to 20 feet wide and 100 feet long. Several gravel-bottomed, clay pits approximately six feet deep are developed in the floor of this room but their relationship to the drainage of the cave is not clear. Speleothems are common in the rear of this room. A third crawlway which is floored with massive flowstone and a few shallow rimstone pools leads into the last room which is 30 feet long and terminates in very treacherous breakdown. During the spring and early summer, it is impossible to enter the cave due to a stream flowing from the cave entrance.
Local residents insist that this cave formerly connected with a sinkhole, 700 yards north of Howell. This may well be "Cave-in-the-Field" which fits this description. Howell Cave is developed in flat lying beds of the Stones River Limestone.
Two hundred yards upriver from Howell Cave is an impressive 5ft.x3ft. entrance in the cliff face, 20 feet above the canal. This has been dubbed Little Howell Cave . From the entrance, a gravel-floored crawlway trends NE for 30 feet. It intersects an eight foot high perpendicular passage which is 20 feet long. A narrow crevice is offset from this passage to the NE for 15 feet and pinches down. Little Howell is in the Stones River Limestone striking N 5º E and dipping 20º E.
A small shelter opens in the cliff face 200 feet upriver from Little Howell. The opening is 6 foot square at the entrance and tapers down to a narrow fissure fifteen feet inside. It is in the Stones River Limestone.