This analysis suggests several brachiopod-based bioevents, such as the conspicuous occurrence of micromorphic, mainly thecideoid representotives, which typify a pre-ETMME marker bed in the I-LS.
undulata, distinctive taxon of the north-African margin and, especially, the first record in the Iberian Peninsula of thecideid marker beds prior to the ETMEE.
Cross sections can be fully customized and edited, including reshaping contacts, adding well headers, selecting which layers to visualize, hanging the cross section on a selected reference datum such as mean sea level or a marker bed
, and exporting the cross section into Voxler 3 for true 3D visualization.
This limestone bed represents an important marker bed
at the top of Paleocene and the base of Eocene formations.
The top of the lower section of the Porters Creek Formation is often marked by an indurated, glauconitic siltstone or mudstone that can be used as a marker bed for structural mapping.
The anticlinal interpretation is preferred because the lower Porters Creek siltstone marker bed elevation change is gradual rather than abrupt as would be expected if a fault boundary were crossed.
While the lithologic sequence as a whole varies little in color, between very pale orange (10YR 8/2) and grayish orange (10YR7/4), the marker bed or boundary layer is clearly distinct with darker shades of olive gray (5Y4/2), depending on the humidity conditions of the outcrops (Maurrasse, 1982b).
The highly angular habit of the volcanic components of this layer is in contrast with tear drop and dumbbell shapes of the microtektites found in the marker bed (Izett et al.
These facts indicate that three of the four marker beds
failed quantitative ink constraints in specific ways.
Recent fieldwork has been focused on examining the stratigraphic relationships between fossil localities and laterally continuous geological marker beds
in the Great Divide Basin.