A composite stratigraphic section from the base of the Council Grove Group through the lower half of the Chase Group was shown in Figures 3 through 7.  The lithologies and prominent paleosol features are represented by symbols that can be interpreted using the key provided.  Flooding surfaces marking the boundaries of meter-scale cycles are marked by arrows on the stratigraphic columns, and the transgressive surfaces defining cyclothem boundaries are indicated by the letters TS.  For a thorough discussion of the entire Permian section in Kansas please see the Kansas Geological Survey Bulletin by West and others (2010).

STOPS 1 and 2

    Roadcuts along K-177 between the Kansas River and I-70 provide a nearly continuous exposure of the Lower Permian section from the Johnson Shale, near the base of the Council Grove Group, to the Florence Limestone Mbr. of the Barneston Limestone of the Chase Group.  Of particular interest along this extended series of roadcuts, are the exposures of the Easly Creek Shale, the Blue Rapids Shale, the Speiser Shale, and the Matfield Shale.

    The Easly Creek Shale (Fig. 11)  is a very silty variegated mudrock unit with poorly-developed paleosols.  The silt content may be eolian in origin.  An interesting feature of this interval is that throughout northeastern Kansas it is marked by a mudstone breccia of variable thickness at its base.  At this locality, clasts are up to a meter across.  Above the breccia, the unit is locally highly faulted.  These are predominantly normal faults, but some also show reverse movement.  Significantly, the base of the Easly Creek is marked by a meter-thick gypsum  bed in the subsurface.  The breccia and faulting could be a result of solution collapse, or, alternatively, it may be tectonic deformation localized by the gypsum  bed.

Figure 11. Easly Creek Shale showing faulted and brecciated mudstone of lower part. The breccia at the base correlates to a gypsum layer in the subsurface.

    The Blue Rapids Shale (Fig. 12) is an excellent unit for examining complex polygenetic paleosol profiles. This interval also illustrates well the transition from calcic paleosols at the base of the variegated mudrock interval, to vertic paleosols at the top. The Blue Rapids also rests on the Crouse Limestone -- the top of which is a platy, somewhat dolomitic, fine-grained limestone with gypsum crystal molds and a restricted mollusk fauna. A climatic trend from relatively arid, to subhumid, to monsoonal is suggested by the sequence from the Crouse through the top of the Blue Rapids (see Miller et al., 1996). The next variegated mudstone interval is the Speiser Shale (Fig. 13) that overlies the intervening Funston Limestone. This paleosol interval shows the same pattern from calcic paleosols with caliche nodules, overlain by mottled paleosols and finally a greenish gray vertic paleosol profile.

Figure 12. The lower Blue Rapids Shale displays the typical stacked and polygenetic paleosols of the lower Permian. Also shown is the transition from a calcic paleosol at the base with caliche nodules to a greenish gray vertic paleosol at the top.

Figure 13. Roadcut showing the top of the Blue Rapids Shale, the Funston Limestone, and the overlying Speiser Shale. The Speiser Shale is characterized in this area by its “barber pole” appearance of stacked thin palsosols horizons.

    The Blue Springs Member (Fig. 14) at the top of the Matfield Shale has numerous intriguing features. It is a rather silty interval with numerous stacked and truncated paleosol profiles. Within the Blue Springs paleosols the upper siltstone horizons are highly rooted but other pedogenic features are largely lacking suggesting that the silt may have accumulated later in soil development during drier climatic conditions. Of special note is that one of the paleosol horizons is marked by locally dense lungfish burrows (Fig. 15). This is consistent with the interpretation that these units represent highly seasonal wet/dry environments. A particularly puzzling feature of the Blue Springs at this locality is the presence of 1 to 2 cm thick carbonate cemented zones that crosscut all lithologic and pedogenic features. The timing and origin of these diagenetic features remains an open question. The Blue Springs is overlain by the massive and cherty Florence Limestone that acts as a prominent terrace former throughout the Flint Hills.

Figure 14. The upper photo shows the Blue Spring Member of the Matfield Shale with its stacked siltstones. These siltstones and silty mudstones typically display abundant root traces. The most prominent of the siltstone beds (shown below) also contains closely packed lungfish burrows.

Figure 15. A close-up of the lungfish burrows in the Blue Springs siltstone. These are closely packed and a high percentage of them contain lungfish bone fragments. This suggests that this population of aestivating lungfish may have died in their burrows as a result of the failure of wet season rains.


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