Limestone and dolomitic limestone, sandstone, siltstone, and phyllite and low-grade metasiltstone and metalimestone that were collectively called “units of uncertain affinities” by Till and others (2011). The older rocks of the Grantley Harbor Fault zone of Till and others (2011) are also included here. Limestone, which forms the majority of the exposed area of the unit, is light-gray- to grayish-orange-weathering, medium-light-gray to medium-dark-gray limestone and dolomitic limestone widely exposed in the Teller quadrangle. “Beds are even to irregular and mostly 2 to 30 cm thick. Much of the unit is parallel laminated, but crossbedding occurs locally and some intervals are bioturbated. Other sedimentary features include fenestral fabric and intraclast conglomerate with clasts as much as 5 cm long. Lime mudstone, in part dolomitic and (or) argillaceous, is the main lithology” (Till and others, 2011). Silt to very fine sand-sized quartz grains are a minor component locally. Metamorphic grade and degree of deformation vary from apparently nonmetamorphosed and undeformed to recrystallized areas that are rich in metamorphic white mica, and are phyllitic or schistose. Till and others (2011) also report CAI values for conodonts that are mostly 4–4.5, but are locally 5 and 6, indicating that temperatures of 190 °C to more than 360 °C were reached. Most exposures of the carbonate rocks are fault-bounded, but Sainsbury (1972) reported that the carbonate rocks transitionally overlie sandstone, siltstone, and phyllite. The underlying clastic unit consists of gray- to orange-weathering, gray to brown, very fine- to coarse-grained, locally calcareous sandstone to siltstone, interbedded with gray to black mudstone and, locally, limestone. Beds are typically less than about 5 cm thick but may be as thick as 20 cm. Climbing ripples, cross beds, parallel and convolute laminae, and graded bedding suggest a turbidite origin (Till and others, 2011). Gray-weathering, sericite-rich pelitic phyllite and brown-weathering calcareous phyllite is nonfossiliferous (Till and others, 2011) and is intruded by gabbro (<gb) that crystallized at about 540 Ma (Amato and others, 2009). Rocks of the Grantley Harbor Fault zone consist of metasiltstone, metasandstone, and phyllite that may be a more deformed and metamorphosed equivalent of the clastic part of this unit (Till and others, 2011). Additionally, thinly layered to laminated, orange- and gray-weathering, color-banded, white to dark-gray metalimestone may be a more metamorphosed equivalent of the carbonate rocks part of this unit. Fossil collections, mostly conodonts, indicate that multiple ages are present (Till and others, 2011). The best controlled conodont assemblages are tightly dated as early-middle Early Ordovician and other collections are early Middle Ordovician (Till and others, 2011). The intruding gabbro (<gb) is earliest Cambrian, which constrains the age of at least part of the unit to Proterozoic. The clastic rocks, also intruded by gabbro in northeastern exposures, have also produced a single conodont of middle Early to Late Ordovician age at one site and conodont fragments of indeterminate Cambrian-Triassic age at two other sites at southern exposures (Till and others, 2011). A detrital zircon sample of sandstone has a major peak in its cumulative probability distribution that is similar to the age of the gabbro at 550 Ma; there are also a large number of zircons of varying Proterozoic age and a few Archean grains (Amato and others, 2009)