On the west face of
The Billings Fold was pictured in the first edition of Marland Billings' "Structural Geology" in 1942. Structurally, the fold lies within the uppermost of three southeast-opening isoclinal synclines. Its fold-axis (N58E at 32°) is almost perpendicular to the cliff face. The axial plane is oriented N16W, 36 NE.
Schists are metamorphic rocks, forming from clays and muds that have been subjected to heat and pressure over time, lots of time. Quartzite is formed in a similar fashion from grains of sand that have collected in rivers, lakes and seas. Actually, most of
How did the Littleton Formation come to be? All of New England, in fact the entire East Coast of the U.S. including the Maritimes of Canada, formed from both small and large land masses that drifted to their present location like slabs of ice floating on a frozen pond. We call that geological process “plate tectonics.” When tectonics plates drift into one another, they interact where they meet, called plate boundaries. The interaction of the plates at their boundaries built a chain of mountains (amongst numerous other geological events). The Littleton Formation began as a continental slope (let’s call it a shoreline) that became squeezed (that’s the heat and pressure part) when the plate containing the land mass of Avalonia slowly collided (the plate tectonic-stuff) into the then-primitive
A schematic depiction from the Late Ordovician of the impending Acadian Orogeny. It involved the collision between the Avalonian "Volcanic Arc" on the right and the proto-North American continent (Laurentia) on the left. Note the region of future "entrapment" of marine shelf and slope areas of what might hypothetically represent the Littleton Formation.
Modified from Janet Zeh (http://www.lisrc.uconn.edu/)
As the Littleton Formation began to form during the “big squeeze,” it folded over on itself, like a rug sliding along a slippery floor. Some of those folds were huge (called nappes, which formed
Compressional forces, such as those encountered in plate collisions, can result in a varied array of landforms.
This is the view looking south from Monte Rosa, a prominent, bald crag on the southwest ridge of Mount Monadnock. Fine views are afforded of the New England coastal plain, central plateau, the Berkshires of western Massachusetts and the Green Mountains of Vermont. The young hiker is croached on a deformed block comprised of schist from the Littleton Formation.