205 W. State St., PO Box 530, Trenton, NJ 08625-0530
2Department of Geological Sciences, California State University-Long Beach,
1250 Bellflower Boulevard, Long Beach, CA 90840
Current work in the Jutland Klippe of Union Township, Hunterdon County, New Jersey has confirmed various past studies of ages ranging from the Adelograptus-Clonograptus Zone to the Climacograptus bicornis Zone. However, the sites currently being studied are in original sequence, not overturned as suggested in some previous publications. To date, no certain overlap has been found in graptolite ages of the Jutland Klippe with those of the main body of the Martinsburg Formation of Delaware Water Gap National Recreation Area.
Throughout this century the Ordovician rocks near
Jutland, Hunterdon County, New Jersey have
presented challenges to structural and paleontological work (Figure 1).
Weller (1903) noted the presence of well-preserved
graptolites there in fair abundance, in contrast with other rocks
of the Ordovician System in New Jersey. Noting the
unusually complicated structure, Weller's report foreshadowed other
efforts to interpret the area, which mostly lies within
Union Township. Various workers sought precise dates,
structural interpretations, and a better understanding of the
Taconic Orogeny, (Dodge, 1952; Perissoratis, 1974; Perissoratis et
al., 1979; Markewicz, 1984; Parris and Cruikshank, 1986).
though the outcrop area is small, the Jutland Sequence (also called the Jutland Klippe) has great potential for interpretation of Taconic-area movements and for comparison to other Ordovician sequences. Among these, the Martinsburg Formation, which overlies the Jacksonburg Formation at Delaware Water Gap National Recreation Area, is the most significant. New faunal information from previously inaccessible exposures near Jutland can now be presented. Some of our results were published in preliminary form (Parris et al., 1995). The information presented herein has confirmed and expanded our preliminary conclusions, but work continues, and the results cannot yet be considered a final report. The ultimate objective of our studies is a comprehensive biostratigraphy that relates the allochthons and outliers to the Martinsburg Formation at Delaware Water Gap National Recreation Area, where previous studies have established a range from the Climacograptus bicornis Zone to the Climacograptus spiniferus Zone (Parris and Cruikshank, 1992). One outlier has thus far been confidently correlated (Parris et al., 1993). The Port Murray Outlier correlates to the Bushkill Member of the Martinsburg Formation and the Corynoides americanus Zone.
Only a few specimens from previous studies have been located thus far in repositories. We have restudied all such materials available to us and have accepted the competent identifications of our predecessors for the most part (Parris et al., 1995).
We also have prospected the Jutland sequence in search of more faunal material, including inspection of sites previously reported. The one major new site, herein described, was inspected in detail for the sake of a more detailed lithologic description of its fossiliferous sequence. It includes the first exposure of a section in which an estimate of thickness is possible, as well as an approximation of the positions of the fossiliferous zones. Results
The Clinton Block and Supply Site in Union Township (Figure 2) is the major source of new information on the Jutland Sequence. Four graptolite-bearing levels have thus far been collected. Although significant deformation is present at the site, these collections are in an apparent sequence, numbered herein as Collections 19-22. The units generally strike N55 oE and dip 24 o SE, in apparent consistency, with collection 19 lowest, and collection 22 highest. Collection 21 is from a metabentonite high in the quarry face. The other collections are from marine clastic units.
Table 1 lists the faunal collections numbered 19-22 as currently identified. Zonation numbers are those of Berry (1960, 1968). Previous collections range from Zone 2 (Adelograptus-Clonograptus) to Zone 12 (Climacograptus bicornis). Those of the Clinton Block and Supply Site are in the later ranges of that span.
Numbers currently assigned to specimens from the Clinton Block and Supply Site are as follows: NJSM 16481-16490 from Locality 19; NJSM 16564 for Locality 20; NJSM 16565 for Locality 21. Specimens from Locality 22 are New Jersey Geological Survey specimens, currently unnumbered, but under study at the New Jersey State Museum.
Exposures of the Jutland section of the Clinton Block and Supply Site enable an approximation of section thickness and notation of key beds (Figures 2 and 3 ). The sequence ranging from the level of Zone 8 to Zone 9 is approximately 50 meters thick and from Zone 9 to Zone 10 another 20 meters.
Table 1Faunal collections numbered 19-22 as currently identified. Zonation numbers are those of Berry (1960, 1968). Previous collections range from Zone 2 (Adelograptus-Clonograptus) to Zone 12 (Climacograptus bicornis). Those of the Clinton Block and Supply Site are in the later ranges of that span.
19 Isograptus forcipiformis (Ruedemann) 8
Didymograptus sp. (extensus?)
Pseudotrigonograptus ensiformis (Hall)
Tetragraptus sp. (bigsbyi or serra)
Xiphograptus svalbardensis (Archer and Fortey)
Isograptus victoriae maximus (Harris)
20 Isograptus sp. 9
Cryptograptus tricornis (Carruthers) Glossograptus sp. (holmi?)
21 Glyptograptus teretiusculus (Hissinger) 10
Dichograptidae, genus indet.
Cryptograptus tricornis (Carruthers)
? Reteograptus geinitzianus Hall
22 Hallograptus? 11
The graptolite biostratigraphy is but one aspect of a structural interpretation. However, the work of Perissoratis et al. (1979) antedates the majority of discoveries at the Clinton Block and Supply site, and the faunal evidence from that site does not support their interpretation, that is, that the sequence is overturned. No previous faunal collections from the Jutland sequence could be compared directly in continuous exposures with measureable sections. The Clinton Block and Supply Site has produced four faunal levels in sequence represented by collections 19-22, which are demonstrably older basal faunas to younger upper faunas. There is no reason to conclude that this differs from the Jutland Sequence as a whole, which thus appears to be an original sequence, not overturned. A new structural interpretation will be expected once other investigations are completed.
The youngest rocks of the Jutland sequence closely approach the ages of the oldest rocks of the Martinsburg Formation, both being correlated to the Climacograptus bicornis Zone. However, no overlap in the ages of the two sequences can yet be demonstrated.
We thank the authorities at the New Jersey Geological Survey for their continued cooperation and encouragement, notably Richard Dalton, Donald Monteverde, and Richard Volkert. The extensive field studies of Frank Markewicz were the basis of much of our investigation. Dr. Constantine Perissoratis gave helpful information on his earlier studies of the area. The help and permission granted by the Clinton Block and Supply Company was essential to our effort.
Berry, W.B.N. 1960. Graptolite faunas of the Marathon region, West Texas: University of Texas Publication 6005, 179p.
. 1968. British and North American Lower Ordovician correlation: Reply:Geological Society of America Bulletin, v. 79, p. 1265-1272.
Dodge, H.W., Jr. 1952. Paleontology and stratigraphy of the shales west of Clinton, Hunterdon County, New Jersey. Unpublished Senior thesis, Princeton University.
Markewicz, F. circa 1984. Geology of the High Bridge 7 1/2' Quadrangle, New Jersey (with accompanying key/legend). Unpublished report on file at Geological Survey of New Jersey.
Parris, D.C. and K.M. Cruikshank. 1986. Ordovician graptolites from a new locality near Jutland, New Jersey: The Mosasaur, v. 3:155-159.
. 1992. Graptolite biostratigraphy of the Ordovician Martinsburg Formation in New Jersey and contiguous areas: N.J. Geol. Surv. Rep. 28, 18 pp.
Parris, D.C., L. F. Miller, and S. C. Finney. 1993. Graptolite Age Determination of the Martinsburg Formation at the Port Murray Outlier, New Jersey. Bulletin of the New Jersey Academy of Science 38(1), 1-3.
. 1995. Graptolite Biostratigraphy at the Jutland Klippe, New Jersey, Geological Association of New Jersey, VXII, Contributions to the Paleontology of New Jersey, p. 240-253.
Perissoratis, C. 1974. Jutland Klippe - A Taconic Type Allochthon in Western New Jersey. Unpublished thesis at Queens College, the City University of New York. 117p.
, P. W. G. Brock, H. K. Brueckner, A. A. Drake Jr., and W. B. N. Berry. 1979. The Taconides of western New Jersey; Evidence from the Jutland Klippe. Geological Society of America Bulletin, v. 90, part I, p. 10-13, part II, p. 154-177.
Weller, S.B. 1903. The Paleozoic faunas: New Jersey Geological Survey, Report on Paleontology, v. 3, 462 p.