If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. The dike dates to the period. Web. Upheaval Dome by a meteoroid impact a mass of salt should exist beneath the . Even so, during the formation of most of the erosion features of this region, the sedimentary layers were not solid rock - they were still relatively soft. Quartz veins and pegmatite are also present. This shot March 17. When geologists first suggested that Upheaval Dome was the result of a salt dome, they believed the land form resulted from erosion of the rock layers above the dome itself. For this section, you will need to know about "Erosional Landforms", p. Upheaval Dome is a striking geologic structure in the Canyonlands. Web. Upheaval Dome is not well dated, but may be the same age as the . Which of the layers of upheaval dome are most resistant to erosion. Upheaval Dome was first thought to be a volcanic crater in the early 1900s. A syncline surrounds the center, where the axis forms a complete circle approximately two miles across. Upheaval Dome is circular depression of folded and faulted rocks located in Canyonlands National Park, Utah. Web. Other Theories Other theories for the origin of Upheaval. Mar 03, 2022 Upheaval Dome was first thought to be a volcanic crater in the early 1900s. The greyish dome in the center rises 750 feet from the floor, a giant belly button surrounded by a rust-colored rim. Explore the mysteries of Upheaval Dome and make a decision for yourself. Web. Explore the mysteries of Upheaval Dome and make a decision for yourself. Igneous rocks are formed when magma (or molten rocks) have cooled down and solidified. Some rock types are easily eroded, while others are more resistant. Because of the extensive erosion by wind and water (episodic flooding) evident at Upheaval Dome, as its name indicates, it. &8221; This photograph of Upheaval Dome was taken by an astronaut onboard the International Space Station. As the term implies, lateral erosion is the erosion that occurs on the sides, or floodplains, of a river or stream, and it is also referr. form was the result of the erosion of rock layers above the dome. Jun 09, 2018 3) Based on the referencing written reports of OGAP and other non-profit agencies, we wrote and submitted Best Management Practices Recommendations to Ron Garcia of Baca National Wildlife Refuge. Some rock types are easily eroded, while others are more resistant. 5-kilometer- (3. Web. Sep 01, 2018 Along the ridges in the Mountainland you can see white lines these are the hardest layers of rock, such as quartzite, which resist erosion. The surrounding layers in CanyonlandsNational Park are relatively flat-lying. Erosion since the impact has washed away any meteorite debris, and now provides a glimpse into the interior of the impact crater, exposing rock layers once buried thousands of feet underground. When geologists first suggested that Upheaval Dome was the result of a salt dome, they believed the land form resulted from erosion of the rock layers above the dome itself. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. Jayma After traveling all over the world, I finally understand where my heart belongs Burma. The alternating rock layers make a nearly circular, 5. What caused these folds at Upheaval Dome Geologists do not know for . Web. 25), it resembles somewhat a volcanic or meteor crater and has been called such by some. Web. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. Resistant sandstones stand tall as circular ridges, outermost of which. Upheaval Dome, San Juan County, Utah, is a complexly deformed circular structure approximately 5 km in diameter, occurring within the Triassic Moenkopi, Chinle, Wingate, and Kayenta and the Jurassic Navajo Formations. There are two theories that explain how it may have formed. Some strata near the center are nearly vertical in orientation. Upheaval Dome in Canyonlands National Park, Utah, is a colorful circular belly button, unique among the broad mesas and deep canyons of the Colorado Plateau. This caused a dome to appear on the surface, an upheaval dome. removed by erosion and the present surface of Upheaval Dome is the pinched-o stem below the missing bubble. Among rock types, igneous rocks, sandstone, and conglomerate resist erosion, while claystone, mudstone, and shale erode easily. Web. Upheaval Dome is one such geographical formation that is difficult to account for with standard theories. com For decades, two theories about the formation of Utah&x27;s Upheaval Dome jostled for supremacy. Five miles northwest of the Y we come to Upheaval Dome, one of the most unusual geographic and geologic features of the park. Although the land around it is flat, the layers that make up Upheaval Dome are layered in a raised circle. 8 billion years old; this is the Central Rand Group, source of more than one-third of all gold mined on Earth. As a result, over millions of years salt can flow up through rock layers as a "salt bubble", rising to the surface and creating salt domes that deform the surrounding rock. Wear- and erosion-resistant materials are of significant interest for different applications, such as industrial devices, aerospace materials, and military equipment, related to their capability. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. Although the land around it is flat, the layers that make up Upheaval Dome are layered in a raised circle. Web. 7 Miles Round-Trip The Crater View Trail runs. Upheaval Dome is an impact crater located in the Island in the Sky. As the area around Upheaval Dome reached equilibrium, the rocks underground heaved upward to fill the void left by the impact. Some strata near the center are nearly vertical in orientation. 5 hr Features Geological Wonders Nearest Town Moab, Ut Is Upheaval Dome caused by a meteor impact. Upheaval Dome as seen from the International Space Station. Architecture photos. Web. The rock layers in the dome form a large ring-shaped feature and are tilted outward in all directions, as shown in the geologic cross section on the next page. The knobby, black crust here includes. Upheaval Dome crater, Utah. Island in the Sky, also known as Between the Rivers, is the most visited and. 25), it resembles somewhat a volcanic or meteor crater and has been called such by some. Upheaval Dome Today. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. Web. UPHEAVAL DOME. burial, metamorphism, melting a. The rim of Upheaval Dome is 3 miles across and over 1000 feet above the core floor. Which of the following would be most consistent with an origin of Upheaval Dome by a meteoroid impact A. The stucture is, according to the University of New Brunswick impact database, less than 170 million years old. The circular structure represents the remnant of a deeply eroded complex impact crater and provides spectacular insights into the architecture of a crater floor. Rocks in the center of the crater have been pushed up . Igneous rocks formed from such magmas are common elsewhere in. What process (es) hashave caused the formation of Upheaval Dome. As a result, V equals 176 ((4. igneous rock comprising the dike is more resistant to erosion than the surrounding rock b. At which location is the greatest amount of sediment most likely being deposited answer choices A B C D Question 10 60 seconds Q. There are two theories that explain how it may have formed. Web. Web. Complete both lessons and answer these multiple-choice questions below. It is approximately 5 km in diameter and estimated to be less than 170 million yrs old. The Upheaval Dome Crater is over 2 miles wide, ringed by downwarped rock layers called a Syncline. Five miles northwest of the Y we come to Upheaval Dome, one of the most unusual geographic and geologic features of the park. Sep 01, 2018 Along the ridges in the Mountainland you can see white lines these are the hardest layers of rock, such as quartzite, which resist erosion. Currently, the most accepted theory of its formation is that it was created by a meteorite erosion has occurred at Barringer Crater. rainfall can coat rocks and soil with a thin film of water, helping them to weather b. Upheaval Dome Today. a mass of salt should exist beneath the crater B. The central peak in the core is 3000 feet in diameter and rises 750 feet from the floor. 5 miles south of the Island in the Sky Visitor Center and turn right (west) onto Upheaval Dome Road. Sediments such as sand and mud were originally deposited near sea level by ancient seas, lakes, marshes, salt flats, and sand dunes. Web. Recent research suggests that a salt bubble as well as the overlying rock have been entirely removed by erosion and the present surface of Upheaval Dome is the pinched off stem below the missing bubble. This caused a dome to appear on the surface, an upheaval dome. removed by erosion and the present surface of Upheaval Dome is the pinched-o stem below the missing bubble. A culverts flow depth can be determined by its channel width and depth. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. solidification, melting, burial c. Upheaval Dome is another interesting feature of the Island in the Sky district. UPHEAVAL DOME. What caused these folds at Upheaval Dome Geologists do not know for . The Triassic and Cretaceous rocks are separated by this type of unconformity an angular unconformity. presence of volcanic fragments scattered around the crater E. When geologists first suggested that Upheaval Dome was the result of a salt dome, they believed the landform resulted from erosion of the rock layers above the dome itself. Web. " source (visit link). Web. Web. 12, page241. Upheaval Dome is not well dated, but may be the same age as the . The leading notions of its creation have held that it is either the deep core of a long-gone salt dome or an eroded meteorite crater. Web. The rock layers in the dome form a large ring-shaped feature and are tilted outward in all directions, as shown in the geologic cross section on the next page. it does not break easily What is the process called when nephrite jade forms when chemical difference between 2 rock layers are smoothed by nature metasomatism If jade is resistant to scratching what is its&x27; hardness on Mohs scale 5. 229-230, especially landforms in areas with horizontal layers. Vredefort Dome, which measures about 90 kilometers across, was observed on June 27, 2018, by the Operational Land Imager (OLI) on Landsat 8. Any rock type that is more resistant to erosion than the rock type below it is called a cap rock. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. The heavy rock pushed down on the salt, creating uneven pressure that led to a budge in the salt layer. . Salt stocks and salt walls are the most classic of salt structures. Web. Dome have. 1999). 25), it resembles somewhat a volcanic or meteor crater and has been called such by some. it does not break easily What is the process called when nephrite jade forms when chemical difference between 2 rock layers are smoothed by nature metasomatism If jade is resistant to scratching what is its&x27; hardness on Mohs scale 5. Evidence is as follows (1) sedimentary strata. SourcesUsage Public Domain. Erosion has created an impressive cross-section of 19 different rock formations. Web. " source (visit link). For most of bulk materials, the product of this time dependency is a well-known erosion curve that consists of five different stages of erosion, each has a different erosion rate. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. The circular structure represents the remnant of a deeply eroded complex impact crater and provides spectacular insights into the architecture of a crater floor. Web. Web. Web. Some strata near the center are nearly vertical in orientation. Web. The bedrock at a certain location is deeply scratched, and in some places is covered by a layer of unsorted sediment. igneous rock comprising the dike is more resistant to erosion than the surrounding rock b. Erosion since the impact has washed away any meteorite debris, and now provides a glimpse into the interior of the impact crater, exposing rock layers once buried thousands of feet underground. The less resistance of the rock eroded more rapidly creating the open pit of the dome. Over time, layers of sediment built up on top of the salt and hardened into sandstone. Web. Enter the email address you signed up with and we&x27;ll email you a reset link. When geologists first suggested that Upheaval Dome was the result of a salt dome, they believed the land form resulted from erosion of the rock layers above the dome itself. In the latter cases, usually an intact, erosion-resistant cap rock. Geologists have now determined that it is not, but until very recently, that was about all that was firmly known. For example, we usually find weak rocks under valleys and strong rocks under hills, ridges, and uplands (Figure 12. Which of the layers of Upheaval Dome are most resistant to erosion The sandstones The mud stones The mud stones with pebbles The layers are all equally resistant to erosion Answer the sandstones Which of the following would be most consistent with an origin of Upheaval Dome by rising magma An indigenous body beneath the crater. Intrusion f&39;i. 5 miles south of the Island in the Sky Visitor Center and turn right (west) onto Upheaval Dome Road. Sandstones and limestones tend to be resistant to erosion in the semiarid climate and thus form cliffs whereas siltstones and shales tend to erode more easily into slopes. Detailed geologic mapping, seismic refraction data, and the presence of shock metamorphosed rocks indicate that the dome originated by collapse of a transient cavity formed by impact. The rock layers in the dome form a large ring-shaped feature and are tilted outward in all directions, as shown in the geologic cross section on the next page. Detailed geologic mapping and seismic refraction data indicate that the dome originated by collapse of a transient cavity formed by impact. Web. Crater View Trail - 1. In the center of the crater there are enormous rocks and many layers of sediments pushed vertically upward forming a dome. masters in artificial intelligence reddit my dog still has diarrhea after metronidazole reddit. Expert Answer. Web. The White Rim White Rim Overlook Trail View from the end of White Rim Trail. Web. The effects of erosion are varied, but the most obvious effect is the removal and destruction of land. Web. Web. Explore the mysteries of Upheaval Dome and make a decision for yourself. removed by erosion and the present surface of Upheaval Dome is the pinched-o stem below the missing bubble. what is the name for the hypothesis about how upheaval dome formed as a large mass of salt flowed upward (low density) and bent the rocks into a dome salt diapir the impact hypothesis for the upheaval dome suggests what was responsible for the up-arching of sedimentary rocks. Expert Answer. Web. Finding the trailhead Drive 6. Its jumble of mismatched rocks, warped layers, and sheer size makes it one of the most unusual geologic features in southeast Utah. Artist of the month. Sep 04, 2016 As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. The rim of Upheaval Dome is 3 miles across and over 1000 feet above the core floor. Understanding royalty-free. Jan 17, 2010 Resistant cap rock will help protect softer rock below it from erosion. Some believe that the dome is a sign of a sub-surface salt dome--a rising plug of relatively low-density salt that caused overlying rock layers to dome up in a circular pattern like a basketball underneath a blanket. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. Upheaval Dome is not well dated, but may be the same age as the . Complete both lessons and answer these multiple-choice questions below. Sediments found in glacial moraines are best described as A)It is located at a high elevation in a. Erosion is dominant at A and C, and deposition is dominant at B and D. Web. Among rock types, igneous rocks, sandstone, and conglomerate resist erosion, while claystone, mudstone, and shale erode easily. Geologists believe Upheaval Dome is either a salt dome or an impact crater. Upheaval Dome is a massive (three miles in diameter) almost-perfectly circular crater cut deep into the many rock layers. As a result, over millions of years salt can flow up through rock layers as a "salt bubble", rising to the surface and creating salt domes that deform the surrounding rock. Transcribed image text Which of the layers of Upheaval Dome are most resistant to erosion 50 m Multiple Choice the sandstones the mudstones the mudstones with. Study with Quizlet and memorize flashcards containing terms like Why would it be inappropriate to use the principal of cross-cutting to determine the relative ages of the sedimentary rock layers from the Upheaval Dome investigations, Which of the layers of Upheaval Dome are most resistant to erosion, Which of the following would be most consistent with an origin of Upheaval Dome by rising. The crater seen today is simply the eroded remains of that dome. Recent research suggests that a salt bubble as well as the overlying rock have been entirely removed by erosion and the present surface of Upheaval Dome is the pinched off stem below the missing bubble. Upheaval Dome is a circular, dome shaped structure. But more than 2 billion years of erosion has made the exact size hard to pin down. READ MORE January 20, 2016 Tags meteorite, Upheaval Dome, utah. A syncline surrounds the center, where the axis forms a complete circle approximately two miles across. Web. Erosion is a process that causes the soil surface to wear out; geological erosion is caused naturally by water, wind or gravity, and accelerated erosion is caused by human use of land. Some layers are more resistant to erosion and form cliffs, whereas others are less resistant and erode into slopes. Web. Scientists debate Upheaval Dome&x27;s origin. There are two theories that explain how it may have formed. Five miles northwest of the Y we come to Upheaval Dome, one of the most unusual geographic and geologic features of the park. Sandstone injectites of Upheaval Dome, Utah,. Erosion since the impact has washed away any meteorite debris, and now provides a glimpse into the interior of the impact crater, exposing rock layers once buried thousands of feet underground. The effects of erosion are varied, but the most obvious effect is the removal and destruction of land. Mar 03, 2022 Upheaval Dome was first thought to be a volcanic crater in the early 1900s. A synclinesurrounds the center, where the axis forms a complete circle approximately two miles across. As the term implies, lateral erosion is the erosion that occurs on the sides, or floodplains, of a river or stream, and it is also referr. The dome was pushed up by the salt domes forcing its way through the sedimentary beds. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. As the area around Upheaval Dome reached equilibrium, the rocks underground heaved upward to fill the void left by the impact. Web. com Science Earth Sciences Earth Sciences questions and answers Which of the layers of Upheaval Dome are most resistant to erosion 50 m Multiple Choice the sandstones the mudstones the mudstones with pebbles The layers are all equally resistant to erosion. The meteorite theory. Details about the erosion curve and its stages are discussed in Refs. naked little mermaid, naked balarena
Because of the extensive erosion by wind and water (episodic flooding) evident at Upheaval Dome, as its name indicates, it wasn&x27;t initially recognized as an impact crater. . Which of the layers of upheaval dome are most resistant to erosion
8 billion years old; this is the Central Rand Group, source of more than one-third of all gold mined on Earth. 4-mile-) diameter &8220;bull&8217;s-eye. Mar 03, 2022 One area breaks this pattern of twisting canyons cut through layers of sandstone Upheaval Dome, in Canyonlands National Parks Island in the Sky District. Web. The Upheaval Dome is the result. For instance, it. Although the land around it is flat, the layers that make up Upheaval Dome are layered in a raised. Erosion since the impact has washed away any meteorite debris, and now provides a glimpse into the interior of the impact crater, exposing rock layers once buried thousands of feet underground. the resistant White Rim Sandstone weathers into. The alternating rock layers make a nearly circular, 5. Scientists debate Upheaval Dome&x27;s origin. What process (es) hashave caused the formation of Upheaval Dome. Upheaval Dome is circular depression of folded and faulted rocks located in Canyonlands National Park, Utah. Web. Erosion since the impact has washed away any meteorite debris, and now provides a glimpse into the interior of the impact crater, exposing rock layers once buried thousands of feet underground. Recent research suggests that a salt bubble as well as the overlying rock have been entirely removed by erosion and the present surface of Upheaval Dome is the pinched off stem below the missing bubble. Some scientists believe that as a result of complex erosional processes, Upheaval Dome is one of the best places in the world to study impact dynamics. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. Explore the mysteries of Upheaval Dome and make a decision for yourself. Small bodies of metamorphosed igneous rocks, called dikes, are found from near Fontana Dam to Clingmans Dome. Upheaval Dome is a circular, dome shaped structure. When geologists first suggested that Upheaval Dome was the result of a salt dome, they believed the land form resulted from erosion of the rock layers above the dome itself. Upheaval Dome crater, Utah. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. One thing, thats not up for debate is that only a 0. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. mai 2018. Although the land around it is flat, the layers that make up Upheaval Dome are layered in a raised. Seismic refl ection studies by Kanbur et al. Viewed from the air (fig. <170 Ma. Evidence is as follows (1) sedimentary strata in the center of the structure are pervasively imbrica. Details about the erosion curve and its stages are discussed in Refs. The geological formation in question is three miles across and roughly circular in shape. Surrounding this dome is a downwarp in the rock layers called a syncline. Upheaval Dome Today. 25), it resembles somewhat a volcanic or meteor crater and has been called such by some. The Upheaval Dome Trail in total is 1. principle 1 the youngest layer is on top, and the oldest is on the bottom. &8221; This photograph of Upheaval Dome was taken by an astronaut onboard the International Space Station. Nov 28, 2022 The JT-60SA tokamaka joint program of fusion research and development agreed and co-financed by the European Atomic Energy Community (Euratom) and the government of Japancould restart cooldown operations and coil energization as early as March 2023, according to an article published by Fusion for Energy (Barcelona), the implementing agency for Euratom. If true, Upheaval Dome would earn the distinction of being the most deeply eroded salt structure on earth. Upheaval Dome, San Juan County, Utah, is a complexly deformed circular structure approximately 5 km in diameter, occurring within the Triassic Moenkopi, Chinle, Wingate, and Kayenta and the Jurassic Navajo Formations. The crater seen today is simply the eroded remains of that dome. It doesn&x27;t have the awesome beauty of Mesa Arch, but it is a. Sep 01, 2018 Along the ridges in the Mountainland you can see white lines these are the hardest layers of rock, such as quartzite, which resist erosion. Web. Web. Quartz veins and pegmatite are also present. Web. In the latter cases, usually an intact, erosion-resistant cap rock. Viewed from the air (fig. As the area around Upheaval Dome reached equilibrium, the rocks underground heaved upward to fill the void left by the impact. The heavy rock pushed down on the salt, creating uneven pressure that led to a budge in the salt layer. The heavy rock pushed down on the salt, creating uneven pressure that led to a budge in the salt layer. Of the many incredible sights in Canyonlands, Upheaval Dome is one of the most intriguing. The various layers of upturned rock eroded at different rates and produced the concentric pattern still visible today. Explore the mysteries of Upheaval Dome and make a decision for yourself. A similar process, weathering, breaks down or dissolves rock, but does not involve movement. Web. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. View the full answer. 25), it resembles somewhat a volcanic or meteor crater and has been called such by some. Jan 01, 1999 Two vastly different phenomena, impact and salt diapirism, have been proposed for the origin of Upheaval Dome, a spectacular scenic feature in southeast Utah. Upheaval Dome is a circular, dome shaped structure. 6 - 1. the dike is very linear, implying that magma likely filled a crack d. Web. It is possible to circle around the entire Upheaval Dome via. 12, page241. In some areas, erosion of the layers has formed buttes and rounded hills. Upheaval Dome as seen from the International Space Station. Upheaval Dome crater, Utah. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. Long Creek Nursery is Ready to Share It&39;s Abundance After many years of gathering and trialing useful and fruitful plants from around the world we have created an Edible Landscape Allstars collection for our region. Which of the layers of Upheaval Dome are most resistant to erosion 50 m Multiple Choice the sandstones the mudstones the mudstones with pebbles The layers are all equally resistant to erosion. Detailed geologic mapping and seismic refraction data indicate that the dome originated by collapse of a transient cavity formed by impact. As the area around Upheaval Dome reached an equilibrium, the rocks underground heaved upward to fill the void left by the impact. Web. Which of the layers of upheaval dome are most resistant to erosion. Five miles northwest of the Y we come to Upheaval Dome, one of the most unusual geographic and geologic features of the park. sedimentary rock layers at Niagara Falls in western New York State. Viewed from the air (fig. Web. The Upheaval Dome is the result. The overlying rock layers were uplifted and then eroded, leaving the bulls-eye surface pattern. Web. Recent research suggests that a salt bubble as well as the overlying rock have been entirely removed by erosion and the present surface of Upheaval Dome is the pinched off stem below the missing bubble. Upheaval Dome is another interesting feature of the Island in the Sky district. solidification, melting, burial c. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. what is the name for the hypothesis about how upheaval dome formed as a large mass of salt flowed upward (low density) and bent the rocks into a dome salt diapir the impact hypothesis for the upheaval dome suggests what was responsible for the up-arching of sedimentary rocks. A disconformity occurs when sediments are moved without being tilted, and these upper layers are then eroded and covered by younger rock. Crater View Trail - 1. Upheaval Dome Today Whatever its origin, Upheaval Dome is a unique and fascinating geologic feature, visible even from space. Viewed from the air (fig. Over time, layers of sediment built up on top of the salt and hardened into sandstone. The crater seen today is simply the eroded remains of that dome. For this section, you will need to know about "Erosional Landforms", p. " source (visit link). This article outlines one theory in particular. A jumbled lower peakthe actual dome. Web. The meteorite theory. Although the land around it is flat, the layers that make up Upheaval Dome are layered in a raised. In the latter cases, usually an intact, erosion-resistant cap rock. Web. 8 miles Elevation Gain 100-150 ft Approximate Hiking Time 1-2. The rim of Upheaval Dome is 3 miles across and over 1000 feet above the core floor. Biological soil crust is just what the name describes - a living soil that creates a crust over the landscape. The crater seen today is simply the eroded remains of that dome. The alternating rock layers make a nearly circular, 5. Web. . nina hartley bbc