 The King s Throne in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 A hall in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 Spacious hall in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 A cave in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 Stalactites in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 Stalagmites in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 The Watchtower in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 Pluto s Anteroom(?) in Northern Cavern in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 Stalagmites in Natural Bridge Caverns. San Antonio, Texas, October 6, 2007
 River Walk underneath a bridge. San Antonio, Texas, October 6, 2007
 "Natural entrance" to Carlsbad Caverns. New Mexico, December 26, 2007
 Serpentine path of "Natural entrance" to Carlsbad Caverns. New Mexico, December 26, 2007
 Weathered stones on a slope of Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Massive stalagmites in Hall of Giants of Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Rocks on a slope of Freshman Mountain east from Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Mission San Juan. San Antonio, Texas, October 6, 2007
 Riverwalk passage under a bridge. San Antonio, Texas, October 24, 2008
 Mall near River Walk. San Antonio, Texas, October 6, 2007
 Church of Mission Espada. San Antonio, Texas, October 6, 2007
 Statue near Mission San Juan. San Antonio, Texas, October 6, 2007
 A church of Mission San Juan. San Antonio, Texas, October 6, 2007
 Riverwalk at evening, view from a foot bridge. San Antonio, Texas, October 24, 2008
 Cacti on a slope of Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 24, 2007
 Passage between stones on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 24, 2007
 A stone bridge (1937) across Heathcote Brook in Cook Natural Area. Kingston, New Jersey, April 28, 2007
 A stone bridge across Heathcote Brook in Cook Natural Area at sunset. Kingston, New Jersey, April 2, 2007
 El Capitan Mountain from southern foot of the mountain. Guadalupe Mountains National Park, Texas, December 27, 2007
 El Capitan Mountain from a trail at the foot of the mountain. Guadalupe Mountains National Park, Texas, December 27, 2007
 Mountain laurel flowers on Blue Trail in DeSoto State Park on Lookout Mountain. Fort Payne, Alabama, May 19, 2007
 River Walk under E. Houston(?) Street Bridge. San Antonio, Texas, February 9, 2008
 Passage in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Bench at River Walk under E. Pecan(?) Street Bridge. San Antonio, Texas, February 9, 2008
 Climbing Turkey Peak in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 A column and other speleothems in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Narrow passage in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Pointed formations in caves of Carlsbad Caverns. New Mexico, December 26, 2007
 Limestone formations in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Flowstone feature in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Massive stalagmites in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Limestone tunnel in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Travertine speleothems along a passage in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Lions Tails hanging in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Stalactites and massive stalagmites in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Lichens on rocks near Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Rocks east from Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Weathering of rocks near Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Cacti east from Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Fresh snow near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 Ocotillo bush near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 Columns in a small side alcove in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Plants in snow near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 El Capitan Mountain at sunset, view from lower Roadside Park south from the mountain. Guadalupe Mountains National Park, Texas, December 28, 2007
 Prickly pear cactus on Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Agaves and cacti in snow near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 Huge stalagmite named "Rock of Ages" in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Cholla cactus in snow near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 Irregularly shaped limestone formations along a passage of Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Stalactites and stalagmites in a small alcove along the side of Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Bone-shaped limestone formations along a passage of Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 A narrow stalagmite with a large cluster of stalactites in the Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Irregularly rounded- or scallop-shaped passages in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Dwarf sunflowers (Old-man-of-the-mountain, Rydbergia grandiflora, Hymenoxys grandiflora) on a slope of Colony Baldy Mountain in Sangre de Cristo Mountains. Colorado, July 3, 2007
 Prickly pears cactus in snow near a road between White s City and Carlsbad Caverns. New Mexico, December 26, 2007
 Drapery and ripple-shaped patterns of travertine flowstone speleothems in Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Speleothems (including stalactites, stalagmites, a column, and helictites) in an alcove of the Big Room of Carlsbad Caverns. New Mexico, December 26, 2007
 Mushroom rocks (differential weathering of shaded sides of rocks) in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Pedestal rock (differential weathering) near Turkey Pass Trail in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 View of Lockhart Hall from arched gate of Blair Hall of Princeton University. Princeton, New Jersey, March 7, 2007
 A tiger behind Whig Hall, with Nassau Hall in background, in Princeton University. Princeton, New Jersey, March 7, 2007
 A waterfall of Cavern Cascade in Watkins Glen State Park. New York, October 9, 2005
 A historical bridge across Millstone River bridge during flooding, near Road 27. Kingston, New Jersey, April 16, 2007
 Weathered surface of Enchanted Rock in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 View to the north from Enchanted Rock in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Standing on a granite dome of Enchanted Rock in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Crass (product of weathering) on Enchanted Rock in Enchanted Rock State Natural Area. Fredericksburg, Texas, October 27, 2007
 Riverwalk at evening. San Antonio, Texas, October 24, 2008
 Alamo mission. San Antonio, Texas, October 24, 2008
 Buzzard s Roost from the top of Freshman Mountain. Enchanted Rock State Natural Area, Fredericksburg, Texas, December 25, 2018
 Veterans Memorial Bridge, also known as Gramercy Bridge, over Mississippi River. Fog is the result of cooling of warm and humid air. Wallace, west from New Orleans, Louisiana, January 7, 2007
 Weathered pedestal rocks at the top of Freshman Mountain. Enchanted Rock State Natural Area, Fredericksburg, Texas, December 25, 2018
 Lace cactus (Echinocereus reichenbachii) on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Mural in Martin Luther King, Jr. Park, near Waco Bridge. Waco, Texas, November 22, 2009
 Historical mural in Martin Luther King, Jr. Park, near Waco Bridge. Waco, Texas, November 22, 2009
 Foggy sunrise at Martin Luther King, Jr. Park, near Waco Bridge. Waco, Texas, November 22, 2009
 Restaurant in area of Navarro Street at Riverwalk at evening. San Antonio, Texas, October 24, 2008
 Hedgehog, or claret cup cactus (Echinocereus triglochidiatus) on the top of Freshman Mountain. Enchanted Rock State Natural Area, Fredericksburg, Texas, December 25, 2018
 A tourist on a trail above Whirlwind Gorge taking a picture of a waterfall of Cavern Cascade in Watkins Glen State Park. New York, October 9, 2005
 A small house on Burnett Street near Martin Luther King Jr. Street. Calvert, Texas, January 28, 2007
 Veterans Memorial Bridge, also known as Gramercy Bridge, over Mississippi River, view from a levee near River Road. Wallace, Louisiana, January 7, 2007
 Moonglow lichen (Dimelaena oreina)(?) on pink granite of Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Blue-edged scale lichen (Psorula rufonigra) on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Thorny cluster of hedgehog, or claret cup cactus (Echinocereus triglochidiatus) on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Rock-shield lichen (Xanthoparmelia) on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Blooming mountain mint (Pycnanthemum tenuifolium) both in natural light and under 365 nm ultraviolet (UV-A) blacklight from Richards Loop Trail in Sam Houston National Forest near Montgomery. Texas, September 6, 2024
 Zigzag cliff-brake fern (Pellaea ovata) in shade of big rocks on Freshman Mountain in Enchanted Rock State Natural Area. Fredericksburg, Texas, December 25, 2018
 Mountain slope behind the ranch near Casper. Wyoming, July 20, 2007
 Skyline Drive in fog in the area of Loft Mountain. Virginia, May 16, 2007
 Area of Loft Mountain at Skyline Drive. Virginia, May 16, 2007
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