Paleontological Report for CNM 2012

Cabrillo National Monument (CABR) in southern California was established to memorialize Juan Rodriguez Cabrillo and his 1542 voyage of exploration. It also protects the Old Point Loma Lighthouse and a variety of natural resources, including an area of intertidal habitats (CABR Figure 1). CABR was proclaimed October 14, 1913, and was transferred from the War Department to the National Park Service on August 10, 1933. Its boundaries have changed several times, on February 2, 1959, September 28, 1974, and July 3, 2000. CABR currently encompasses 64.73 ha (159.94 acres), all of which is under federal administration (CABR Figure 2).

Geologic Background

CABR is located in San Diego County at the southern tip of Point Loma, a north-south trending peninsula that separates San Diego Bay on the east from the Pacific Ocean to the west. Downtown San Diego is just over 8 km (5 miles) to the northeast, across the bay. North Island Naval Air Station and the city of Coronado, at the north end of the Silver Strand, are just east of the southern tip of Point Loma. A broad coastal plain, marked by flat-topped mesas dissected by west-flowing ephemeral streams and rivers, extends from the shoreline east to foothills of the Peninsular Ranges.

Tidepools
CABR Figure 1. An intertidal area of CABR (photo courtesy Thomas Deméré).

A geologic resource evaluation scoping session, coordinated by the Geologic Resources Division of the National Park Service (NPS), was held for CABR during May 2008 (KellerLynn 2008). The initial paleontological resource inventory and summary was prepared by Koch and Santucci (2003). Other references that describe the paleontology and geology of CABR or its immediate vicinity at the end of Point Loma include Berry (1922), Stephens (1929), Webb (1937), Matsumoto (1959, 1960), Anderson (1962), Valentine (1961), Valentine and Meade (1961), Sliter (1968), Bukry and Kennedy (1969), Kennedy and Moore (1971), Bowersox (1974), Kern and Warme (1974), Ku and Kern (1974), Kennedy (1975a, 1975b), Wilson (1976), Kern (1977), Dawson (1978), Nilsen and Abbott (1979), Sundberg (1979), Popenoe and Saul (1987), Bannon et al. (1989), Kern and Rockwell (1992), Saul and Popenoe (1992), Bukry (1993), Muhs et al. (1994, 2002, 2003), Abbott (1999), Rahman and Droser (2003), Hunt et al. (2006), von Dassow and Droser (2006), Kennedy and Tan (2008), Taylor (2008), and Squires and Saul (2009). Point Loma as a whole is both extensively fossiliferous and extensively documented in the literature.

The geologic history recorded in the sedimentary rocks exposed at CABR is confined to the Late Cretaceous and Pleistocene (see the appendix for a geologic time scale). The San Diego area is part of the Peninsular Ranges terrane (distinct block of continental crust). It is sometimes reported that the terrane was not accreted to the North American craton until the middle of the Cenozoic (Morris et al. 1986; Lund and Bottjer 1992; Ford and Kirkland 2001), but it now appears that the terrane had accreted by the time CABR’s Late Cretaceous rocks were being deposited (Grove and Bebout 1995; Tan and Kodama 1998; Symons et al. 2003; Vaughn et al. 2005).

The Upper Cretaceous rocks of CABR were deposited on a submarine sediment fan, in part by west-flowing sediment gravity flows (Nilsen and Abbott 1979; Bartling and Abbott 1983). The water depth at this time may have been 900 to 1000 m (2,900 to 3,300 ft) (Almgren 1973). Sediment came from the ancestral Peninsular Ranges to the east (Nilsen and Abbott 1979), which during Late Cretaceous time formed a Andean-style mountain range just landward of an active subduction zone. The ancient Farallon oceanic plate was being subducted beneath the North American continental plate causing regional uplift and exposure of older plutonic (granitic) rocks (Abbott 1999). This mountain-building episode, known as the Laramide Orogeny (Girty 1987), also affected large areas of western North America as far east as present-day Colorado. Meanwhile, the ancient Point Loma submarine fan was depositing sediment into a deepening marine basin. The fan prograded across the floor of this basin and over time formed a thick accumulation of turbidite sandstones, middle-fan channel-fill sandstones and mudstones, and inner-fan channel-fill conglomerates (Nilsen and Abbott 1979).

A hiatus of approximately 70 million years separates the Cretaceous rocks of CABR from the much younger veneer of Pleistocene landforms and unconsolidated deposits. Although only partially documented within CABR, the Upper Cretaceous–Eocene geology of San Diego is related to the Upper Cretaceous–Eocene geology of Channel Islands National Park (CHIS; see the CHIS summary in this report for more details). The islands, which are part of a small crustal block that has moved north and rotated clockwise since the Late Cretaceous, would have been a short distance south of San Diego during the Late Cretaceous, and record the deposition of a similar submarine fan (Bartling and Abbott 1983). Later, during the Eocene, the block had moved north far enough to juxtapose the future site of the islands with the San Diego area, resulting in the accumulation of the same type of conglomerates (Bartling and Abbott 1983).

The Pleistocene geology of the San Diego area includes a series of uplifted marine terraces; CABR has excellent examples of some of these terraces (T. Deméré, pers. comm., November 2011). Sixteen marine terraces and associated deposits are known from San Diego County, ranging from perhaps 1.29 Ma (million years) to 80,000 years old (Kern and Rockwell 1992). Several terraces are exposed within CABR, including, from oldest to youngest, the Linda Vista, Nestor, and Bird Rock terraces (KellerLynn 2008). They date to approximately 855,000 years ago (Linda Vista), 120,000 years ago (Nestor), and 80,000 years ago (Bird Rock) (Kern 1977; Wehmiller et al. 1977; Kennedy et al. 1982; Kern and Rockwell 1992). The various terraces are now much higher than their original elevations; the San Diego region is being uplifted at an average rate of 0.13–0.14 m (5–6 in) per thousand years (Kern and Rockwell 1992). The beginning of the Holocene coincided with the arrival of humans to the area; humans were present in the Carlsbad area 55 km (34 miles) to the north by the Early Holocene (Rick and Erlandson 2000).

Geologic units exposed within CABR include, from oldest to youngest: the Point Loma Formation and Cabrillo Formation of the Rosario Group (Upper Cretaceous); lower–middle Pleistocene paralic (coastal) deposits; and two sets of upper Pleistocene paralic deposits (Kennedy 1975b; Kennedy and Tan 2008). The terminology for the paralic deposits has changed over time. Kennedy (1975a, 1975b) included the oldest paralic deposits in the Lindavista Formation, and the younger paralic deposits in the Bay Point Formation. Later, Kennedy and Tan (2008) attached no formal names to the deposits, and differentiated two units within Kennedy’s (1975a, 1975b) Bay Point Formation. The older formation names are still widely used, although the city of San Diego has switched to using the generic terms (T. Deméré, pers. comm., November 2011). Because the pre-existing NPS digital geological map of CABR uses the generic terms, this document will use these terms as well to maintain continuity. However, the older terms will be described. The Point Loma Formation, Cabrillo Formation, and upper Pleistocene paralic deposits are fossiliferous within CABR (CABR Table 1), which also has specimens in museum collections.

Map
CABR Figure 2. Geography of CABR (NPS).
Startigraphic Table
CABR Table 1. Concise tabulation of CABR stratigraphy, fossils, and depositional setting; details and references can be found in the text.

Sources of Paleontological Resources

The fossils of CABR present opportunities for education, interpretation, and continued or future scientific research in the monument. Fossils have been described since the late 19th century from Point Loma. Cooper (1894) discussed some of the early collecting. Among the 19th century material Cooper noted is a specimen of the coiled ammonite Heteroceras found associated with a coal shaft north of CABR on the west coast of the peninsula, and a specimen of the straight ammonite Baculites chicoensis collected on the surface near the lighthouse. Several species of Cretaceous invertebrates were named during this early period. Cooper (1894) named the bivalves Crassatella lomana, Corbula triangulata, and Crenella santana, and the gastropods Cerithium fairbanksi, Stomatia intermedia, Calliostoma kempiana, Siphonaria capuloides, and Tornatella normalis from Point Loma, and Anderson (1902) named the gastropod Haliotis lomaensis from the Upper Cretaceous Cabrillo Formation (then referred to as the “Chico Formation” because of their similarity to Cretaceous rocks in northern California).

Recalling the “flying ammonite” (see the Park Collections section), another large ammonite has been found recently near the southwest corner of the monument, just within or just outside of the boundary (T. Deméré, pers. comm., November 2011). Fossils constantly erode from the Pleistocene marine terrace deposits of the monument (T. Deméré, pers. comm., November 2011).

Rosario Group: Point Loma Formation (Upper Cretaceous)

The Point Loma Formation is exposed along the west side of Point Loma. It was named from a locality just outside of CABR, near the extreme southern tip of the peninsula below the new Point Loma lighthouse (Kennedy and Moore 1971; Kennedy 1975a). Approximately 83 m (270 ft) of the formation is exposed above sea level at this locality, with at least another 190 m (620 ft) present below low tide. This unit is composed of interbedded layers of dusky yellow sandstone and olive-gray clay-rich shale, with beds about 30 cm (12 in) thick (Kennedy 1975a). On the south end of Point Loma, the lower half includes interbedded sandstone and mudstone, and the upper half is mostly mudstone (Kern and Warme 1974). The contact with the overlying Cabrillo Formation is conformable (Kennedy 1975a). These two formations were not differentiated until 1971 (Kennedy and Moore 1971); before this, these two units were called the Rosario Formation. Fossils in the formation indicate a Late Cretaceous age (middle or late Campanian to early Maastrichtian) (Kennedy 1975a). Fossils from just north of CABR, at the Point Loma Waste Water Treatment Plant, date to about 75.5 to 74.5 Ma, and slightly younger fossils are present in the steep slope behind the plant (Bukry 1993).

The Point Loma Formation formed as a submarine fan (Bannon et al. 1989) that accumulated on the outer continental shelf, slope, and rise (Kennedy and Moore 1971). It includes mudstones interpreted as representing the continental slope and basin plain, and sandstones representing lagoonal, shelf, fan lobe, and fan channel settings (Nilsen and Abbott 1979). Foraminifera (amoeba-like protists that form “shells”) from strata exposed at the tip of Point Loma indicate a bathyal environment (broadly, the continental slope), with some specimens of sublittoral foraminifera transported downslope from the adjacent continental shelf (Sliter 1968). The formation’s foraminiferal assemblage has been compared to that of the modern assemblage on the continental slope and in deep basins in the eastern Pacific Ocean (Sliter 1975). The formation’s trace fossils also generally indicate bathyal settings (Kern and Warme 1974). Limited biological disturbances of the sediment (bioturbation) indicate that the oxygen content of the water was low (Sliter 1975).

Marine microfossils and molluscs are well represented in the Point Loma Formation, although many other types of fossils have been found. Single-celled organisms are represented by coccoliths (structural plates from some types of algae, also known as calcareous nannofossils) (Bukry 1993, 1994) and foraminifera (Anderson 1962; Sliter 1968, 1975). Terrestrial plants are represented by a cycad leaf recovered from CABR (Koch and Santucci 2003), angiosperm leaves (T. Deméré, pers. comm., February 2012), and wood (Kern and Warme 1974; Nilsen and Abbott 1979). Marine invertebrates are represented by bryozoans (moss animals) (Taylor 2008), brachiopods (lamp shells) (Nilsen and Abbott 1979), bivalves (Sundberg 1981; Saul and Popenoe 1992; Squires and Saul 2009), ammonites (including coiled and straight [Baculites] forms; Matsumoto 1959, 1960), gastropods (Popenoe and Saul 1987; Loch 1989; Saul 1988), scaphopods (tusk shells) (Coombs and Deméré 1996), crabs (Bishop 1988), ostracodes (seed shrimp) (Coombs and Deméré 1996), echinoids (sea urchins) (Sundberg 1979; Coombs and Deméré 1996), and trace fossils (Kern and Warme 1974), including possible worm tubes (Sliter 1975). Most trace fossils are found in mudstone (Kern and Warme 1974). The vertebrate assemblage includes sharks (Coombs and Deméré 1996), holocephalians (ratfish and related cartilaginous fish) (T. Deméré, pers. comm., November 2011), ray-finned fish (Coombs and Deméré 1996), mosasaurs (KellerLynn 2008), and dinosaurs, including hadrosaurs (Ford 1999) and the armored dinosaur Aletopelta coombsi (the first dinosaur named from California), which is either an ankylosaurid (Ford and Kirkland 2001) or a nodosaurid (Coombs and Deméré 1996; Hawakaya et al. 2005).

The Point Loma Formation is fossiliferous within CABR. The most unusual fossil is a large cycad leaf, collected by R. A. Cerutti and B. O. Riney in 1994 from a tide pool (Koch and Santucci 2003). It is currently on display at the San Diego Natural History Museum (SDNHM 48361, from SDNHM locality 3774) (T. Deméré, pers. comm., November 2011). Abundant invertebrate trace fossils, particularly of the trace genera Ophiomorpha and Thalassinoides, can be found in outcrops around the monument’s tide pools (CABR Figure 4) (B. Pister, CABR Chief of Natural and Cultural Resources Management, pers. comm., December 2011; D. Vaughn, Senior Project Geologist, Geotechnical Exploration Inc., and CABR volunteer, pers. comm., December 2011). These trace fossils are found in densities of 2 to 10 per m2; wave action continually exposes new trace fossils and erodes previously exposed examples (D. Vaughn, pers. comm., December 2011). Greater Point Loma has been an important area for Point Loma Formation fossils, including coccoliths (Bukry 1993), foraminifera (Sliter 1968), bryozoans (Taylor 2008), bivalves (Saul and Popenoe 1992; Squires and Saul 2009), ammonites (Matsumoto 1960; Bannon et al. 1989), gastropods (Popenoe and Saul 1987), and trace fossils (Kern and Warme 1974). Large ammonites with attached bivalves, and a partial mosasaur lower jaw have been found north of the monument boundary (Koch and Santucci 2003; KellerLynn 2008), as well as one of the rare hadrosaur specimens (Hilton 2003; T. Deméré, pers. comm., November 2011).

Ophiomorpha
CABR Figure 4. Ophiomorpha in the Point Loma Formation at CABR (photo courtesy Donald Vaughn).

Rosario Group: Cabrillo Formation (Upper Cretaceous)

The Cabrillo Formation is exposed in central CABR (Kennedy 1975b; Kennedy and Tan 2008). It was named from a locality 250 m (820 ft) east of the new Point Loma lighthouse, where it is 81 m (270 ft) thick and composed of structureless (massive) sandstone and cross-bedded conglomerate. Farther north, the formation reaches a thickness of 170 m (560 ft) (Kennedy 1975a). Sandstone-dominated and conglomerate-dominated sections can be differentiated, and both are present at CABR (Kennedy 1975b; Kennedy and Tan 2008). Mudstones are also included in the formation (Dawson 1978; Nilsen and Abbott 1979). The unit has a Maastrichtian age (Taylor 2008).

The Cabrillo Formation represents continued deposition of the submarine fan that was active during deposition of the Point Loma Formation (Nilsen and Abbott 1979; Girty 1987; Bannon et al. 1989). New facies include mudstones from turbidity currents and conglomerate from fan channel fills (Nilsen and Abbott 1979). The lowest part of the formation was part of the inner section of the submarine fan (Girty 1987; Bannon et al. 1989).

The Cabrillo Formation is not generally as fossiliferous as the Point Loma Formation. Fossils reported from the formation include coccoliths (Bukry and Kennedy 1969), foraminifera (Anderson 1962), wood fragments (Dawson 1978), corals (Dawson 1978; Sundberg 1979), bryozoans (Taylor 2008), brachiopods (Dawson 1978), bivalves (Dawson 1978; Bannon et al. 1989; Kennedy and Shiller 2011), ammonites, gastropods (Dawson 1978; Bannon et al. 1989), echinoderms (Dawson 1978), and a shark tooth (Koch and Santucci 2003; Hunt et al. 2006). Many fossils discovered in the Cabrillo Formation are reworked, from the underlying Point Loma Formation or from older deposits of the Cabrillo Formation itself (Dawson 1978; T. Deméré, pers. comm., November 2011). For example, fossils reported by Dawson (1978) primarily came from rip-up clasts (rock fragments) of siltstone, meaning they had already undergone some lithification (becoming stone) once before. The only fossils not found in clasts were rare examples of abraded and damaged shells, belonging to robust shallow-water bivalves like Coralliochama orcutti, Ostrea sp., and Spondylus striatus (Dawson 1978). Similarly, a single bivalve shell was the only fossil reported by Kennedy (1975a) that was not reworked.

The Cabrillo Formation is fossiliferous within CABR. Dawson (1978) collected fossils from a series of localities along the sea cliffs on the east side of Point Loma, extending into CABR (SDNHM locality 2823; T. Deméré, pers. comm., November 2011). A shark tooth, from the genus Squalicorax, was found in a clast recovered from a channel cut into sandstone (Koch and Santucci 2003) either just within or just outside of northern CABR (SDNHM specimen 35963, SDNHM locality 3272; T. Deméré, pers. comm., November 2011). It too is probably reworked (T. Deméré, pers. comm., November 2011). Point Loma in general has yielded many fossils from the Cabrillo Formation. Aside from Dawson’s (1978) finds and the shark tooth, coccoliths (Bukry and Kennedy 1969), foraminifera (Anderson 1962), and bryozoans (Taylor 2008) have also been reported from the formation on the peninsula.

Old paralic deposits of Unit 6 and 7 (Bay Point Formation [sensu lato]) (late Pleistocene)

The upper Pleistocene paralic deposits of CABR are associated with two major marine terraces: the older Nestor Terrace, at elevations of about 22 to 23 m (72 to 75 ft) above sea level, and the younger Bird Rock Terrace, at about 9 to 11 m (30 to 36 ft) above sea level. Around San Diego, these deposits consist of siltstone, sandstone, and conglomerate, deposited in strandline, beach, and estuarine settings, and as colluvium (sediment transported by gravity, such as around slopes and cliffs) (Kennedy and Tan 2008). These deposits, particularly those associated with the Nestor Terrace, are also known as the Bay Point Formation (see for example Kennedy 1975a, 1975b). At CABR, the Bay Point Formation is complex and includes marine sediments grading up to nonmarine sediments (T. Deméré, pers. comm., November 2011). There are no Pleistocene deposits younger than the Bird Rock Terrace than can be mapped at a scale of 1:24,000 at CABR (Kennedy 1975b; Kennedy and Tan 2008).

The Nestor and Bird Rock terraces were formed during sea-level highstands that date to approximately 120,000 and 80,000 years ago, respectively (Wehmiller et al. 1977; Kennedy et al. 1982; Muhs et al. 1994, 2002). The marine terraces cut during these highstands are found around the world (Muhs et al. 1994). The Nestor Terrace highstand was perhaps 6 m (20 ft) higher than the modern sea level (Muhs et al. 1994), and appears to be associated with water temperatures similar to those found off of San Diego today (Muhs et al. 2006), or slightly warmer (Kennedy et al. 1982; Kennedy 1999). During Nestor Terrace time, Point Loma was an island (Kern 1977). The Bird Rock Terrace sea level highstand was 2 m (7 ft) or more lower than the modern sea level (Kern and Rockwell 1992), and the water was cooler (Kennedy et al. 1982; Kennedy 1999; Muhs et al. 2006; Kennedy and Rockwell 2009). An intermediate 100,000-year-old terrace is not as well preserved (Muhs et al. 1994), but is present on Point Loma (Muhs et al. 2003). These terraces were all formed during the last interglacial complex, preceding the most recent extensive glaciation (Muhs et al. 2002). Older publications sometimes refer to them as being from the Sangamon (Kern et al. 1971; Moore 1972), a term derived from an interglacial soil in Sangamon Co., Illinois, but no longer used for marine deposits of the last interglacial period.

The upper Pleistocene paralic deposits of the San Diego area are extensively fossiliferous. Approximately 275 species have been identified from the Nestor Terrace (Kern 1977), and more than 250 from the Bird Rock Terrace (Kennedy and Shiller 2011). The Nestor Terrace assemblage includes corals, chitons (sea cradles), bivalves, gastropods, scaphopods, barnacles (Kern 1977), crabs (T. Deméré, pers. comm., November 2011), echinoids, and worm tubes (Kern 1977). The Bird Rock Terrace assemblage includes coralline algae, corals, bryozoans, brachiopods, chitons, bivalves, gastropods, scaphopods, polychaete worms, barnacles, decapod crustaceans (crabs, lobsters, and allies), echinoids, sponge borings, shark teeth, stingray teeth and stingers, and bony fish otoliths and miscellaneous bones (Kennedy and Shiller 2011). The Bay Point Formation (in the broad sense) as a whole has a fossil assemblage including foraminifera (Kern 1971; Bowersox 1974; Kennedy 1975a), sponges, corals, brachiopods (Kennedy and Shiller 2011), chitons, bivalves (Kern et al. 1971), scaphopods (Valentine 1959), ostracodes (Holden 1968; Kern 1971; Bowersox 1974; Kennedy 1975a), echinoids (Valentine 1959; Kennedy and Shiller 2011), worm tubes, the ray Myliobatis (Kern et al. 1971), and shark teeth, Rare land mammals including tapirs (Jefferson 1989), ground sloths, mastodons, mammoths, horses, and camels (T. Deméré, pers. comm., November 2011) have been found in nonmarine sediments broadly assigned to the Bay Point Formation. Reworked Pliocene fossils have also been reported by Stephens (1929) and Kern et al. (1971).

The upper Pleistocene deposits of CABR are very fossiliferous. The SDNHM has four fossil localities from the Nestor Terrace within CABR (SDNHM localities 58, 121, 457, and 5635) (T. Deméré, pers. comm., November 2011). Bivalve and gastropod fossils from localities 58 and 121 were reported as far back as 1929 (Stephens 1929). Locality 58 has yielded the gastropod Littorina, locality 121 yielded 13 taxa of bivalves and gastropods, and locality 457 yielded the coral Balanophyllia elegans, the chitons Lepidozona californiensis and Stenoplax conspicua, 41 taxa of bivalves and gastropods, the barnacle Tetraclita sp., and the crab Pachygrapsus crassipes, according to the SDNHM online collections database. SDNHM locality 5635 is the same as San Diego State University (SDSU) locality F2521, a Nestor Terrace locality discussed by Kern (1977). SDSU locality F2525 yielded 5 chiton species, 13 bivalve species, 38 gastropod species, the barnacle Tetraclita rubescens, and the echinoids Dendraster excentricus and Strongylocentrotus sp. (Kern 1977). The records of the SDNHM for locality 5635 add sponges, bryozoans, decapod crustaceans, and bony fish to the list. SDNHM locality 5635 has unusual fossils from a more protected facies of the unit, and warrants additional investigation (T. Deméré, pers. comm., November 2011).

Fossils from the younger Bird Rock Terrace have been recovered from locations just north of CABR on Point Loma and as far north as Ocean Beach (Kennedy and Rockwell 2009; Kennedy and Shiller 2011). Fossils include sponges, corals, bryozoans, brachiopods, chitons, bivalves, gastropods, scaphopods, polychaete worms, barnacles, decapod crustaceans, echinoids, shark and ray teeth, and bony fish remains (Webb 1937; Kennedy and Shiller 2011). Muhs et al. (1994, 2002) obtained uranium-thorium dates on corals from the Bird Rock and Nestor terraces north and south of CABR on Point Loma. Corals that have yielded 100,000-year dates have also been recorded by Muhs et al. (2003). The solitary coral Balanophyllia elegans is often used for dating the terraces (Muhs et al. 1994, 2002). Gastropods from the Nestor Terrace on Point Loma have been found encrusted by contemporaneous bryozoans, worms, barnacles, and other gastropods (Rahman and Droser 2003). Worm-encrusted Pleistocene bivalves have also been found around the peninsula (von Dassow and Droser 2006). Other accounts of late Pleistocene fossils from Point Loma include Berry (1922), Valentine (1961), Valentine and Meade (1961), Bowersox (1974), and numerous unpublished paleontological monitoring and mitigation reports for the City of San Diego Development Services Department.

Potential Sources of Paleontological Resources

Fossils have not yet been documented from the lower–middle Pleistocene paralic deposits within CABR. However, this unit is known to preserve fossils elsewhere in the San Diego area, and future field investigations within the monument may recover fossils from it.

Undivided very old paralic deposits (Lindavista Formation) (lower–middle Pleistocene)

The lower–middle Pleistocene paralic deposits of CABR and the vicinity were formed on wave-cut platforms and preserved by uplift (Kennedy and Tan 2008). Within CABR, they are found in relatively small areas at the higher elevations of the monument (Kennedy 1975b; Kennedy and Tan 2008). These deposits have also been referred to as the Lindavista Formation (Hanna 1926; Kennedy 1975a), and are associated with the Linda Vista Terrace, which is found at about 120 m (390 ft) above sea level (Moore 1972; Kern and Rockwell 1992). Deposits on the terrace are about 2 to 10 m (7 to 33 ft) thick (Moore 1972), and date to a highstand that occurred approximately 855,000 years ago (Kern and Rockwell 1992). The Lindavista Formation is noted for the hematite cement that binds its sediments and provides some resistance to erosion (Hanna 1926; Kennedy 1975a).

The fossil assemblage of the Lindavista Formation is not as diverse as that of the younger terrace units discussed previously, and it is not known to be fossiliferous at CABR. Fossils include bivalves, gastropods, barnacles, echinoids, and worm tubes (Kennedy 1973). The best material is known from the Tierrasanta community near Murphy Canyon, over 23 km (14 miles) to the northeast (Kennedy 1973). The assemblage suggests littoral to shallow sublittoral depths derived from two main habitats, an “exposed open coast sandy beach, and a cobble or rocky bottom” (Kennedy 1973). Rare remains of marine vertebrates, including shark teeth and baleen whale ribs, have been recovered from the Lindavista Formation in Mira Mesa, over 27 km (17 miles) northeast of CABR (T. Deméré, pers. comm., February 2012). Land animals are not known from the Lindavista Formation, but slightly older rocks in eastern San Diego County have yielded extensive vertebrate fossils, as part of what is known as the Vallecito Creek Local Fauna. Thousands of vertebrate specimens from over 2,000 localities are known, including remains of sharks, bony fish, frogs, turtles, lizards, and diverse birds and mammals (Cassiliano 1999). These fossils are indicative of the vertebrates that existed at about the time of the formation of the Linda Vista Terrace.

Park Collections

Cultural artifacts make up almost all of CABR’s collections (B. Pister, pers. comm., January 2012). Formerly, the Visitor Center had a cast of a fossil known informally as the “flying ammonite” on display. The actual fossil was collected near CABR from the rocky beach on the east side of Point Loma in 1975 and is in the collections of the Natural History Museum of Los Angeles County, Los Angeles (LACM) (Wilson 1976). It received its nickname because a helicopter was used to recover it from the boulder beach where it was found. It is a specimen of the species Pachydiscus catarinae; a much smaller individual was found within it, and possibly represents a juvenile that was being brooded inside the adult’s shell, in a similar manner to the modern paper nautilus (Wilson 1976).

Several institutions have records of fossil localities within CABR: the LACM (G. Kennedy, Brian F. Smith & Associates, Inc., pers. comm., March 2012); the San Diego Natural History Museum (SDNHM) (Stephens 1929; Dawson 1978; T. Deméré, pers. comm., November 2011); San Diego State University (SDSU) (Kern 1977); and the University of California Museum of Paleontology, Berkeley (UCMP), which has fossils collected from CABR that were previously at USGS-Menlo Park (G. Kennedy, pers. comm., March 2012). SDSU fossils from CABR can be found in the collections of the LACM and SDNHM. Additionally, Cooper’s (1894) fossils, some of which may be from CABR, are probably at the California Academy of Science (CAS) in San Francisco, and fossils collected from the tip of Point Loma for various graduate projects may have been at UCLA at one time (G. Kennedy, pers. comm., March 2012); UCLA collections are now at LACM.

The LACM has fossils from three Pleistocene-age terrace localities collected by Thomas Deméré for the then-San Diego State College (now University): LACM IP5139, 5140, and 5142 (G. Kennedy, pers. comm., March 2012). Specimens from CABR are on display at the SDNHM, including the cycad leaf from the Point Loma Formation (Koch and Santucci 2003). SDNHM collections include 1,765 specimens from CABR localities: 145 specimens of the gastropod Littorina from locality 58, on the Nestor Terrace; 81 specimens of bivalves and gastropods from locality 121, on the Nestor Terrace; 169 specimens of marine invertebrates, mostly bivalves and gastropods, from locality 457 on the Nestor Terrace; 211 specimens of marine invertebrates from locality 2823, in the Cabrillo Formation; the Squalicorax tooth from locality 3272, in the Cabrillo Formation; the cycad leaf from locality 3774, in the Point Loma Formation; and 1,157 specimens of marine animals, mostly bivalves and gastropods, from locality 5635 on the Nestor Terrace. Locality 5635 is another site which was collected originally as an SDSU site (T. Deméré, pers. comm., November 2011). The UCMP has in its collections fossils from USGS-Menlo Park site USGS M6705, another Pleistocene site from the east site of Point Loma in CABR (G. Kennedy, pers. comm., March 2012).

 

Paleontological Resource Management, Preliminary Recommendations

  • Coastal erosion and landslides are important threats to paleontological resources at CABR. There is little that can be done to mitigate in the case of erosion because fossils that erode from the sea cliffs are removed almost immediately by coastal processes (KellerLynn 2008). Thomas Deméré (pers. comm., November 2011) suggested that preparing detailed descriptions of measured stratigraphic sections (bed-by-bed descriptions of exposures) could effectively summarize the distribution of fossiliferous zones in the sedimentary rocks of CABR, which could help focus management efforts.
  • Invertebrate trace fossils are located in the tide pool area, incurring inevitable human contact and erosion. Some kind of interpretation, possibly combined with blocking off some of the fossils, has been proposed in the past. The continuous wave erosion makes protection unfeasible, but an interpretative sign or placard (that could be moved as erosion dictates) might be a way to enhance the visitor experience.
  • The monument should consider future field inventories for paleontological resources to more fully document in situ occurrences of fossils. The monument may consider a formal site documentation and condition assessment for significant fossil localities. Monitoring of significant sites should be undertaken at least once a year in the future. A Geologic Resource Monitoring Manual by the Geological Society of America and NPS Geologic Resources Division includes a section on paleontological resource monitoring (Santucci et al. 2009).
  • Monument staff should be encouraged to observe exposed sedimentary rocks and associated eroded deposits for fossil material while conducting their usual duties. Staff should photo-document and monitor any occurrences of paleontological resources that may be observed in situ. Fossils and their associated geologic context (surrounding rock) should be documented but left in place unless they are subject to imminent degradation by artificially accelerated natural processes or direct human impacts. [The monument may want to consider establishing some sort of protocol for salvaging fossils in imminent danger of erosion.] When opportunities arise to observe paleontological resources in the field and take part in paleontological field studies with trained paleontologists, monument staff should take advantage of them.
  • Fossils found in a cultural context should be documented as other fossils, but will also require the input of an archeologist. Any fossil with cultural context may be culturally sensitive as well (e.g. subject to NAGPRA) and should be regarded as such until otherwise established. The Geologic Resources Division can coordinate additional documentation/research of such material.
  • Future infrastructure developments or archeological excavations should consider scheduling site monitoring by a trained paleontologist in order to document and protect fossil resources.
  • Contact the NPS Geologic Resources Division for technical assistance with paleontological resource management issues.

Last revised 08-Sep-14

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