Report for the Cheyenne River Range Allotment Management Plan Environmental Analysis

Effects on Paleontological Resources

November 18, 2015

Barbara A. Beasley Nebraska National Forests and Grasslands Supervisor’s Office 125 N. Main Street Chadron, NE 69337 (308) 432-0333 Introduction

This report discloses the effects of proposed activities to paleontological (fossil) resources within the boundaries of the Cheyenne River Range Allotment Management Plan. The spatial boundary used to evaluate direct and indirect consequences was the plan boundary, since no paleontological resources outside of this area will be affected by proposed project activities.

Information and data collected per Special Use Permit reports and paleontological resource inventory survey Passport in Time Project in July 2014 was used to determine the extent of the richness of paleontological resources within in the Cheyenne River Range Allotment Management Plan project area (CRPAMP). Paleontological resources differ from other resources as the fossils are preserved throughout the geological unit in which they are preserved. All geological units in this project area are very fossiliferous. The Paleontology PIT findings reinforced the richness of the fossil resources within the Indian Creek area.

The No Action Alternative (Alternative 1) proposes that no management activities take place within the project area. The Action Alternatives (Alternatives 2 and 3) propose various activities in the pastures noted in the Cheyenne River Range Allotment Management Plan. With respect to this project, the alternatives are very similar in the activities proposed. The action alternatives only differ in the placement and construction of several as yet unidentified range improvements. The Determination of Effects presented in this report takes into consideration the effect of the activities proposed in all action alternatives on the paleontological resources.

Affected Environment/Existing Condition

In order to address paleontological resources the geologic units are discussed as well. The geologic units are listed stratigraphically (oldest to youngest). The northern portion of the project area is underlain by Late Cretaceous Pierre Shale; this unit is marine and ranges in age from 95 to 65 million years ago (mya). This formation is the remainder of the Western Interior Seaway that extended from present Canada to the Gulf of Mexico. There is a hiatus of deposition, while the Black Hills are forced upwards, draining the Western Interior Seaway. Moving south in the project area toward the Badlands National Park north boundary, the Tertiary Chadron Formation forms grayish-green haystack- shaped mounds. This formation is terrestrial (48 to 36 mya) preserving a humid subtropical environment. Located at the very south end of the project, are the Tertiary Brule and Sharps formations (36 to 26 mya). The Brule and Sharps formations form the steep sloped spires seen near Sheep Mountain Table and southern boundary of the CR RAMP. These formations preserve the continuing drying climate and change in biota to accommodate the changing environment.

Figure 1. Looking South from the entrance of Indian Creek Proposed Wilderness Area and Cheyenne River RAMP project area. Foreground is Pierre Shale covered by grasses and brush; middle ground is the Chadron Fm., and the steep slopes in the background are the Brule and Sharps formations. Photo by B.A. Beasley.

Figure 1, shows the landscape of the CRRAMP project, looking south toward Sheep Mountain Table, located on Badlands National Park. This view alone encompasses over 95 million years of sedimentary deposits and natural history that occurred in this area of the Buffalo Gap National Grassland. Environments changed from a deep marine interior seaway, preserving marine reptiles, turtles, some the size of squashed Volkswagens, fish up to 17 feet long, flying reptiles, invertebrates, sharks, and flying and diving toothed birds. The reptiles are not dinosaurs; present evidence indicates that dinosaurs were terrestrial.

Sometime around 65 mya, volcanos erupted along what we know as the Pacific coast. These volcanos belched volcanic ash. Silica (volcanic glass shards) is a major component of volcanic ash. The ash that blanketed the landscape is a paleontologically bitter-sweet situation. The glass shards literally choked the life out of the fauna and flora, causing death; however, it is due to the high silica concentration that has also preserved the Tertiary life.

The Black Hills began to raise around 65 mya, as magma from deep below the surface (caused by volcanoes in the west), forced its way upward. Evidence suggests that the Black Hills are still rising, as the area stream and rivers are cutting into their western banks. During this upwards movement, the Western Interior Sea began to drain while deposition of sediments, in western South Dakota halted. This was a 17 mya hiatus of deposition and acceleration of erosion, while the Black Hills reached their current height. The presence of the Black Hills changed the weather and wind patterns. The western volcanoes continued to erupt and volcanic ash continued to rain down on the landscape. After the valleys west of the Black Hills filled with ash; the eruptions continued, falling on the landscape immediately east of the Black Hills, forming the Tertiary geologic units on the Buffalo Gap National Grassland.

Tertiary Volcanic Province

Both from White River Badlands, Benton et.al, 2015

Generalized Stratigraphic Column of the Indian Creek Allotment and CR CRAMP

30-28 mya

30 mya

34-30 mya

37-34 mya

Black Hills Uplift & Erosion

75-69 mya

Pierre Shale, late Cretaceous, is a dark gray to black marine shale with stringers of bentonite (decomposed volcanic ash) and layers of nodules that are recognizable over long distances. This formation records the last major transgression of the epicontinental Western Interior Seaway. Fossils include ammonites, snails, clams, crabs, mosasaurs, plesiosaurs, fish (including sharks), turtles, pterosaurs, and flightless and flying toothed birds are common in the Sharon Springs member, even occasional dinosaur bones have been found. Counties for Nebraska National Forests and Grasslands: In South Dakota: Pennington, Fall River, Shannon, and Jackson counties. (Bryant, Laurie and Secord, Ross, Forest Service Paleontological Resource Broadscale Assessment and Classification, Agreement No. 1102-0002-96-032). Pierre Shale,

Western Interior Seaway location during the Late Cretaceous, created the deposits of the Pierre Shale Formation.

Archelon, Courtesy of the Peabody Museum of Natural History, Yale University extinct giant sea turtle known from fossilized remains found in North American rocks of the Late Cretaceous epoch. Archelon, protected by a shell similar to that found in modern sea turtles, reached a length of about 3.5 m (12 feet). The front feet evolved into powerful structures that could efficiently propel the great bulk of Archelon through the water.

Chadron Formation Late Eocene has been mapped in North and South Dakota, and Nebraska. The Ahearn, Crazy Johnson, and Peanut Peak members, named in the Big Badlands of South Dakota, are recognizable only in the area of Indian and Battle Creeks, Pennington Co., SD. Titanotheres (Brontotheres), huge rhinoceros-like animals (eight feet at shoulders) occur and are common in the Chadron Formation (Fm), but had become extinct by the time of the overlying Brule Fm. was deposited.

The greyish Chadron Formation was deposited between 34 and 37 million years ago by rivers across a flood plain. Each time the rivers flooded, they deposited a new layer on the plain. Alligator fossils indicate that a lush, subtropical forest covered the land. Most fossils found in this formation are from early mammals like the three-toed horse and the large titanothere.

Brontothere

Brule Formation Middle-Late Oligocene is primarily pinkish siltstones and claystones, with some greenish channels sandstones. Where is best exposed in Nebraska and South Dakota, the Brule Fm. is divided into a lower Scenic Member, and an upper Poleslide Member. Weathering produces steep, tread-and-riser exposures, which may be nearly vertical in the upper member. The Scenic Member contains abundant nodular concretions and includes the Metamynodon Channels, named for the aquatic rhinoceros found in them. Near the top of the Poleslide Member are the coarse-grained Protoceras Channels, the primary source for these small, horned artiodactyls.

Protoceras, an extinct artiodactyl

Sharps Formation Late Oligocene, massive pinkish volcaniclastic siltstones and mudstones as much as 350 feet thick. Calcareous concretions are prominent and often contain vertebrate fossils. The Sharps Fm. is distributed in southwestern South Dakota and northwestern Nebraska. The High potential areas includes South Dakota counties include Pennington, Shannon, Washabaugh, Bennett, Jackson, and Todd. Many kinds of vertebrates found in the White River Group persist at least into the lower Sharps Formation. Among those that first appear in the Sharps Fm. are a diminutive sabertooth cat about the size of a bobcat, the last North American primate Ekgmowechashala, hedgehogs, true moles, mountain beavers, and aplodontid rodents. The uncommonly good preservation and relative abundance of vertebrates in the Sharps Fm. make this unit significant. Its position immediately overlying the White River Group makes possible detailed studies of successional faunas between those very well-known geologic units.

Ekgmowechashala, “Little man who walks upright”, 1st discovered by J. C. Harksen, SDSM&T.

Environmental Effects for All Action Alternatives

Paleontological Resources Rapid Assessment System (PRRAS). Resulting from PRPA, fossils are not assessed a “significance” as this term was never incorporated into the law; leaving this term usage to National Environmental Policy Act. PRPA distinguishes between common and not common plant and invertebrate fossils; it doesn’t distinguish between invertebrate, plant, and vertebrate fossils, as did past Forest Service policy. The reason behind PRPA language is that paleontological resources are to be managed through the use of scientific principals and expertise. There are scientifically important plant, invertebrate, and vertebrate fossil resources; the past policy did not take into consideration that there are scientifically important plant and invertebrate fossils, as it singled out vertebrates being the only “important” fossil resources. Therefore, through the PRRAS, fossils are now mapped as “Fossil Occurrence Unlikely”, “Fossil Occurrence Unknown”, and “Fossil Occurrence Likely”. See map to the right.

Direct Effects

With respect to the Cheyenne River Range Allotment Management Plan project, direct effects are those that will occur during project implementation. The potential for adverse impacts of grazing activities on management relevant paleontological resources relates directly to the level of range developments (i.e. water tanks, pipelines, etc.), number and density of livestock within an allotment, length of grazing periods, other ground disturbing activities existing and proposed within the project area, not withstanding, access to range developments. Livestock grazing has the potential to adversely impact management relevant paleontological resources through trampling, obliteration, and displacement These adverse impacts do not necessarily occur within the span of a single season or a year; adverse effects are cumulative and result from continued, long-term grazing operations. Wet periods often increase the adverse impacts to paleontological resources found at or near the surface. Fossils located within the vicinity of livestock congregation areas, such as near water tanks, salt licks, gates, along fence lines or other livestock trials, suffer the most damage. The severity of grazing impacts on paleontological resources increases proportionally with the number and duration of livestock congregation. Livestock grazing requires the construction and maintenance of range improvements, including water tanks, pipelines, fences, and access roads. The installation and maintenance of range improvements typically require new ground disturbance. Projects requiring new ground disturbance, by definition, have the potential to impact paleontological resources and a ground surface inventory is required.

In general, the design criteria on the paleontological resources of the various activities that are proposed for this project include the following in order to achieve no adverse effect on paleontological resources within the Cheyenne River RAMP:

1. In those portions of the project area where no paleontological resources are present, proposed project activities have No potential to affect paleontological resources.

2. In those portions of the project area in which ground disturbing activities would be carried out, where paleontological resources are present, and where avoidance is feasible and is implemented, the proposed project activities are expected to have No Effect on paleontological resources. Please include in the design criteria, if fossil resources are discovered during the ground disturbing activity; the ground disturbance will cease or ground disturbance path will avoid the resource. If avoidance is not feasible, please contact a qualified paleontologist, preferably an FS paleontologist, to extract the specimen(s), so that the project will continue with as little of a delay as possible creating a No Effect on these newly discovered paleontological resources.

3. In those portions of the project area in which prescribed burning would be carried out, where paleontological resources are present, the project activities are expected to have No Effect on paleontological resources. The fossils preserved in the Chadron, Brule, and Sharps formations are very well preserved with silica and tend to withstand prescribed burns in areas with little vegetation.

4. In portions of the project area in which prescribed burning would be carried out, where paleontological resources are present in the Pierre Shale, the project activities are expected to have No Effect. Therefore, for projects taking place on Pierre Shale; design criteria will be developed that would result in a finding of No Effect to paleontological resources in the Pierre Shale. Typically, the design criteria will include avoidance or resource retrieval.

Geologic Map of CR RAMP shows the geologic units found within the project boundary. Pierre Shale (green) and White River Group geologic units that underlie the recent sediments.

Indirect Effects

In the case of the Cheyenne River Range Allotment Management Plan Project Area, increased site vulnerability is expected to be the principal indirect effect to paleontological resources resulting from proposed activities. Livestock grazing can lead to erosion and exposure, which can in turn lead to an increased risk of vandalism and fossil theft. With application of design criteria as avoidance, it is not expected that the proposed project activities will increase visitor use in those areas in which paleontological resources are located.

Consistency with the Forest Plan

Design Criteria are the preferred action pursuant to the 2001 Forest Plan. Paleontological resources will be understood to require the either avoidance or allowing fossil removal and placement in an acceptable repository in order to preserve these resources.

Consistency with Laws and Regulations

The Paleontological Resource Preservation Act (PRPA), 2009, is not a mitigative law; as the National Environmental Policy Act, 1976 is the basis for designing the criteria of scientifically important resources to have a finding of no effect to these resources. Paleontological resources are to be managed with scientific principals while using scientific expertise.

Paleontological Resources are a Minerals and Geology Management program element under FS directives at 2800/2880 (Geologic Resources, Hazards, and Services) and also FS Manual chapters 2880.2, 2880.3, 2880.42, and 2884.11. Administration of paleontological resources is governed by the Paleontological Resources Preservation Act (PRPA) of 2009 (Pub. L. 111–011, Title VI, Subtitle D, Sec. 6310), and Forest Service regulations for Paleontological Resources Preservation at 36 CFR Part 291, which implement requirements of the PRPA and became effective on May 18, 2015.

Respectfully Submitted

Barbara A. Beasley USFS Paleontologist, Minerals and Geology, Washington Office