|Juana Lopez Member|
Stratigraphic range: Turonian
|Unit of||Carlile Formation|
|Overlies||Codel Sandstone member of the Carlile|
|Thickness||0–6 feet (0.0–1.8 m)|
|Primary||Sandstone with abundant carbonate fossil grains|
|Other||Gravel, Codel fragments|
|Named for||Mesita Juana Lopez Grant, six miles northwest of Los Cerrillos, New Mexico|
Juana Lopez refers to both the uppermost member of the Carlile Shale formation and to the environment that caused it to form. This unit is calcareous sandstone of Turonian age, Upper/Late Cretaceous series in the southern and western Colorado and northern and central New Mexico.
Where present, the Juana Lopez is "the most enigmatic" member of the Carlile Shale. It consists of sand with a large content of indistinguishable grains of fragmented coral, shells (especially inoceramid prisms), sharks teeth, bone, etc. It smells of sulfur when freshly broken. It formed on wide, shallow marine shelf, with strong wave action, but with little sediment coming in from land. It was exposed on the land surface between the retreat of the Greenhorn cycle and the advance of the Niobrara cycle of the Western Interior Seaway.
- Russell K. Lewis, Stratigraphy and depositional environments of the Late Cretaceous (Late Turonian) Codell sandstone and Juana Lopez members of the Carlile shale, southeast Colorado, 2013 - Mines Theses & Dissertations, retrieved 2018-08-14