What is Echolocation? 
 
 Echolocation is the use of sound waves and echoes to determine where objects are in space. Bats use echolocation to navigate and find food in the dark. To echolocate, bats send out sound waves from the mouth or nose. When the sound waves hit an object they produce echoes. The echo bounces off the object and returns to the bats' ears. Bats listen to the echoes to figure out where the object is, how big it is, and its shape. 
 
 Using echolocation, bats can detect objects as thin as a human hair in complete darkness. Echolocation allows bats to find insects the size of mosquitoes, which many bats like to eat. Bats aren't blind, but they can use echolocation to find their way around very quickly in total darkness. 
 
 Bat echolocation, visualized. The sounds that the bat makes are represented by the yellow sound waves; the purple sound waves show the sound waves that are reflecting off of the moth. The bat uses these returning sound waves to figure out the location of the moth. 
 
 What Sounds Do Bats Make? 
 
 The following image shows the sonogram of a silver-haired bat screech from the Western Ecological Research Center. In this recording you can hear a standard repeated call that is for basic navigation. Bats use this to avoid flying into objects. The faster clicking is likely because the bat has detected an insect and the bat needs more accuracy to catch its prey. You can use the player below to listen to the call or get the mp3 file here. 
 
 Your browser does not support this audio element. 
 
 A sonogram, or sound graph, showing the screech of a silver-haired bat. 
 
 Did you know that other animals use echolocation too? Dolphins, whales, shrews and some birds use echolocation to navigate and find food. There are even some blind people that have learned to use echolocation to navigate within their surroundings. 
 
 Humans cannot hear ultrasonic sounds made by echolocating bats. But there are some insects that can hear these ultrasonic sounds. These insects include some moths, beetles, and crickets. When moths hear an echolocating bat, some will turn and fly away. Others will start flying in a zigzag, spiral, or looping pattern to avoid being eaten by the bat. Some crickets and beetles are known to make clicking sounds that startle the bat and scare it off thus avoiding being eaten. 
 
 Did you know that the scientists that developed the sonar and radar navigation systems used by the military got their idea from studying bat echolocation? Just like bat echolocation, sonar uses sound waves to navigate and determine the location of objects like submarines and ships. Only sonar is used underwater, while bats echolocate in the open air. Radar uses electromagnetic waves to determine the location of objects like planes and ships. Like bat echolocation, radar is also used on open air. 
 
 Sound waves and sound reflection is used by bats and dolphins to echolocate; this process was studied and used to develop underwater sonar that we use in submarines and other water vessels. 
 
 
 
 
 
 

 Barrett , BE , Murray , T , Clark , R and Matsuoka , K ( 2008 ) Distribution and character of water in a surge-type glacier revealed by multifrequency and multipolarization ground-penetrating radar . J. Geophy. Res. , 113 ( F4 ), F04011 (doi: 10.1029/2007JF000972 ) 
 
 Benn , DI and Evans , DJA ( 2010 ) Glaciers and glaciation , 2nd edn . Routledge , London 
 
 Bingham , RG , Nienow , PW , Sharp , MJ and Boon , S ( 2005 ) Subglacial drainage processes at a High Arctic polythermal valley glacier . J. Glaciol. , 51 ( 172 ), 15 – 24 (doi: 10.3189/172756505781829520 ) 
 
 Black , RF and Bowser , CJ ( 1968 ) Salts and associated phenomena of the termini of the Hobbs and Taylor Glaciers, Victoria Land, Antarctica . Extracts of “Commission of Snow and Ice” General Assembly of Bern , 79 , Sept.-Oct., 226 – 238 
 
 Black , RF , Jackson , ML and Berg , TE ( 1965 ) Saline discharge from Taylor Glacier, Victoria Land, Antarctica . J. Geol. , 73 ( 1 ), 175 – 181 
 
 Boon , S and Sharp , M ( 2003 ) The role of hydrologically-driven ice fracture in drainage system evolution on an Arctic glacier . Geophys. Res. Lett. , 30 ( 18 ) (doi: 10.1029/2003GL018034 ) 
 
 Burrough , PA and McDonell , RA ( 1998 ) Principles of geographic information systems . Oxford University Press , NY , 190 
 
 Carmichael , JD , Pettit , EC , Hoffman , M , Fountain , A and Hallet , B ( 2012 ) Seismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica . J. Geophys. Res. , 117 ( F3 ), F03004 (doi: 10.1029/2011JF002221 ) 
 
 Catania , G and Paola , C ( 2001 ) Braiding under glass . Geology , 29 ( 3 ), 259 – 262 (doi: 10.1130/0091-7613(2001) 029<0259:BUG> 2.0.CO;2 ) 
 
 Davis , JL and Annan , AP ( 1989 ) Ground-penetrating radar for high resolution mapping of soil and rock stratigraphy . Geophys. Prospect. , 37 ( 5 ), 531 – 551 (doi: 10.1111/j.1365-2478.1989.tb02221.x ) 
 
 DigitalGlobe . ( 2005 ) WorldView 2 1030010009AB3C00, Standard, Percent Reflectance Calculated . Polar Geospatial Center , St. Paul, MN . Copyright 2011, DigitalGlope, Inc. 
 
 Doherty , BT and Kester , DR ( 1974 ) Freezing-point of seawater . J. Mar. Res. , 32 ( 2 ), 285 – 300 
 
 Doran , PT , Kenig , F , Lawson Knoepfle , J , Mikucki , JA and Lyons , WB ( 2014 ) Radiocarbon distribution and the effect of legacy in lakes of the McMurdo Dry Valleys, Antarctica . Limnol. Oceanogr. , 59 ( 3 ), 811 – 826 (doi: 10.4319/lo.2014.59.3.0811 ) 
 
 Elston , DP and Bressler , SL ( 1981 ) Magneto-stratigraphic studies in Neogene deposits of Taylor Valley and McMurdo Sound, Antarctica . J. Roy. Soc. New Zeal. , 11 ( 4 ), 481 – 486 (doi: 10.1080/03036758.1981.10423337 ) 
 
 Fountain , AG , Lewis , KJ and Doran , PT ( 1999a ) Spatial climate variation and its control on glacier equilibrium line altitude in Taylor Valley, Antarctica . Global. Planet. Change , 22 ( 1 ), 1 – 10 (doi: 10.1016/S0921-8181(99)00020-X ) 
 
 Fountain , AG and 12 others ( 1999b ) Physical controls on the Taylor Valley ecosystem, Antarctica . BioScience , 49 ( 12 ), 961 – 971 (doi: 10.1525/bisi.1999.49.12.961 ) 
 
 Glen , JW ( 1958 ) The flow law of ice: a discussion of the assumptions made in glacier theory, their experimental foundations and consequences . I.A.S.H. Publ. , 47 , 171 – 183 
 
 Harper , JT , Bradford , JH , Humphrey , NF and Meierbachtol , TW ( 2010 ) Vertical extension of the subglacial drainage system into basal crevasses . Nature , 467 , 579 – 582 (doi: 10.1038/nature09398 ) 
 
 Higgins , SM , Denton , GH and Hendy , CH ( 2000a ) Glacial Geomorphology of Bonney drift, Taylor Valley: Antactica . Geogr. Ann. A. , 82 ( 2/3 ), 365 – 389 (doi: 10.1111/j.0435-3676.2000.00129.x ) 
 
 Higgins , SM , Hendy , CH and Denton , GH ( 2000b ) Geochronology of Bonney Drift, Taylor Valley, Antarctica: evidence for interglacial expansions of Taylor Glacier . Geogr. Ann. A. , 82 ( 2/3 ), 391 – 409 (doi: 10.1111/j.0435-3676.2000.00130.x ) 
 
 Hoffman , MJ , Fountain , AG and Liston , GE ( 2008 ) Surface energy balance and melt thresholds over 11 years at Taylor Glacier, Antarctica . J. Geophys. Res. , 113 ( F4 ), F04014 (doi: 10.1029/2008JF001029 ) 
 
 Hubbard , A Lawson , W , Anderson , B , Hubbard , B and Blatter , H ( 2004 ) Evidence for subglacial ponding across Taylor Glacier, Dry Valleys, Antarctica . Ann. Glaciol. , 39 ( 1 ), 79 – 84 (doi: 10.3189/172756404781813970 ) 
 
 Jacobel , RW , Christianson , K , Wood , AC , DallaSanta , KJ and Gobel , RM ( 2014 ) Morphology of basal crevasses at the grounding zone of Whillans Ice Stream, West Antarctica . Ann. Glaciol. , 55 ( 67 ), 57 – 63 (doi: 10.3189/2014AoG67A004 ) 
 
 Jenson , SK and Domingue , JO ( 1988 ) Extracting topographic structure from digital elevation data for geographic information system analysis . Photogramm. Eng. Rem. S. , 54 ( 11 ), 1593 – 1600 
 
 Johnston , RR , Fountain , AG and Nylen , TH ( 2005 ) The origin of channels on lower Taylor Glacier, McMurdo Dry Valleys, Antarctica, and their implication for water runoff . Ann. Glaciol. , 40 ( 1 ), 1 – 7 (doi: 10.3189/172756405781813708 ) 
 
 Keys , JR ( 1979 ) Saline discharge at the terminus of Taylor Glacier . Antarct. J. U.S. , 14 , 82 – 85 
 
 Kowalski , J and 36 others ( 2016 ) Navigation technology for exploration of glacier ice with maneuverable melting probes . Cold Reg. Sci. Technol. , 123 , 53 – 70 (doi: 10.1016/j.coldregions.2015.11.006 ) 
 
 Lawrence , J and 6 others ( 2016 ) Subsurface hypersaline brine discharge from Taylor Glacier into Lake Bonney at depth. Poster presented at SCAR Open Science Conference. Kuala Lumpur, Malaysia 
 
 Lyons , B and 6 others ( 2005 ) Halogen geochemistry of the McMurdo dry valleys lakes, Antarctica: Clues to the origin of solutes and lake evolution . Geochim. Cosmochim. Acta. , 69 ( 2 ), 305 – 323 (doi: 10.1016/j.gca.2004.06.040 ) 
 
 Macheret , YY , Moskalevsky , MY and Vasilenko , EV ( 1993 ) Velocity of radio waves in glaciers as an indicator of their hydrothermal state, structure and regime . J. Glaciol. , 39 ( 132 ), 373 – 384 
 
 Mikucki , JA and Priscu , JC ( 2007 ) Bacterial diversity associated with Blood Falls, a subglacial outflow from the Taylor Glacier, Antarctica . Appl. Environ. Microbiol. , 73 ( 12 ), 4029 – 4039 (doi: 10.1128/AEM.01396-06 ) 
 
 Mikucki , JA , Foreman , CM , Sattler , B , Lyons , WB and Priscu , JC ( 2004 ) Geomicrobiology of Blood Falls: an iron-rich saline discharge at the terminus of the Taylor Glacier, Antarctica . Aquat Geochem , 10 , 199 – 220 
 
 Mikucki , JA and 8 others ( 2009 ) A contemporary microbially maintained subglacial ferrous “ocean” . Science , 324 , 397 – 400 (doi: 10.1126/science.1167350 ) 
 
 Mikucki , JA and 8 others ( 2015 ) Deep groundwater and potential subsurface habitats beneath an Antarctic dry valley . Nat. Commun. , 6 , 6831 (doi: 10.1038/ncomms7831 ) 
 
 Murray , T and 6 others ( 2000 ) Glacier surge propagation by thermal evolution at the bed . J. Geophys. Res. , 105 ( B6 ), 13491 – 13507 (doi: 10.1029/2000JB900066 ) 
 
 Pettit , EC , Whorton , EN , Waddington , ED and Sletten , RS ( 2014 ) Influence of debris-rich basal ice on flow of a polar glacier . J. Glaciol. , 60 ( 223 ), 989 – 1006 (doi: 10.3189/2014JoG13J161 ) 
 
 Robinson , PH ( 1984 ) Ice dynamics and thermal regime of Taylor Glacier, South Victoria Land, Antarctica . J. Glaciol. , 30 ( 105 ), 153 – 160 
 
 Schenk , T and 5 others ( 2004 ) SDEM generation from the Antarctic LIDAR data . (USGS Site Report) US Geological Survey , Reston, VA 
 
 Shreve , RL ( 1972 ) Movement of water in glaciers . J. Glaciol. , 11 ( 62 ), 205 – 214 
 
 Smith , BME and Evans , S ( 1972 ) Radio echo sounding: absorption and scattering by water inclusion and ice lenses . J. Glaciol. , 11 ( 61 ), 133 – 146 
 
 Tarboton , DG , Bras , RL and Rodriguez–Iturbe , I ( 1991 ) On the extraction of channel networks from digital elevation data . Hydrol. Process. , 5 , 81 – 100 
 
 Tzanis , A ( 2010 ) MATGPR Release 2: a freeware MATLAB® package for the analysis & interpretation of common and single offset GPR data . FastTimes , 15 ( 1 ), 17 – 43 
 
 Van der Veen , CJ ( 1998 ) Fracture mechanics approach to penetration of bottom crevasses on glaciers . Cold Reg. Sci. Technol. , 27 , 213 – 223 (doi: 10.1016/S0165-232X(98)00006-8 ) 
 
 Wolovick , MJ , Bell , RE , Creyts , TT and Frearson , N ( 2013 ) Identification and control of subglacial water networks under Dome A, Antarctica . J. Geophys. Res.-Earth , 118 , 140 – 154 (doi: 10.1029/2012JF002555 ) 
 
 Wright , AP and 12 others ( 2012 ) Evidence of a hydrological connection between the ice divide and ice sheet margin in the Aurora Subglacial Basin, East Antarctica . J. Geophys. Res. , 117 ( F1 ), F01033 (doi: 10.1029/2011JF002066 ) 

 Team Solves 100-year-old Mystery of Antarctica Waterfall 
 
 Jessica Badgeley ’15, who graduated from Colorado College magna cum laude as a geology major and math minor, is the lead author of a study published in the Journal of Glaciology that solves a 100-year-old mystery surrounding Blood Falls, a red waterfall in Antarctica. 
 
 During the fall semester of her junior year at CC, Badgeley worked with University of Alaska Fairbanks glaciologist Erin Pettit and her team, seeking to understand why the waterfall sporadically would release iron-rich salty water, or brine. The brine exits the end of Taylor Glacier in East Antarctica, turning red from air contact as it descends 60 to 80 feet to the shore of a frozen lake below. 
 
 Pettit said she enlisted Badgeley to lead the study while she was still an undergraduate student to help with the overall mission of understanding the hydrological “plumbing” of cold-based glaciers. “Jessica’s work is a perfect example of the high level of work undergraduate students can do when you give them a challenge and set the expectations high,” says Pettit. 
 
 Badgeley was named a Goldwater Scholar her junior year at CC and currently is a graduate student at the University of Washington in the Department of Earth and Space Sciences. 
 
 New evidence links Blood Falls to a large source of salty water that may have been trapped underneath Taylor Glacier for more than a million years. The study, “An englacial hydrologic system of brine within a cold glacier: Blood Falls, McMurdo Dry Valleys, Antarctica,” maps the pathway this salty water takes from underneath the glacier to where it emerges as a red waterfall flowing over the glacier ice. The pathway has been a mystery since Blood Falls was discovered in 1911 by Griffith Taylor. 
 
 “The salts in the brine made this discovery possible by amplifying contrast with the fresh glacier ice,” says Badgeley. “Now we can tackle the challenge of understanding the role of liquid water — salty or fresh — in other extremely cold glaciers or permafrost environments.” 
 
 One of the study’s exciting findings, says Badgeley, is that liquid water can persist inside extremely cold glaciers, in this case 0°F, without freezing, something that scientists previously thought was nearly impossible. 
 
 Taylor Glacier is known as a cold-based glacier, which means the core of the glacier is persistently below freezing everywhere and its bottom remains frozen to the ground. More commonly, glaciers have a significant amount of ice that is at the freezing point (32°F) and very close to melting. 
 
 Pettit says that the flow of water in a cold glacier is possible because of how water freezes. “While it sounds counterintuitive, water releases heat as it freezes, and that heat warms the surrounding colder ice,” she says. This source of heat within Taylor Glacier combines with the lower freezing temperature of salty water (brine) to make brine movement in the extremely cold ice possible. “Taylor Glacier is now the coldest known glacier to have persistently flowing water.” 
 
 The research team used a technique called radio echo sounding, or radar, to detect and image the pathway of brine within the glacier. The method uses two antennae — one to transmit electrical pulses and one to receive the signals. 
 
 “We moved the antennae around the glacier in grid-like patterns so that we could ‘see’ what was underneath us inside the ice, kind of like a bat uses echolocation to ‘see’ things around it,” said coauthor Christina Carr, who is a doctoral student at the University of Alaska Fairbanks. 
 
 The salts in the brine made the image possible because they create a large contrast to freshwater glacier ice. 
 
 The resulting image clearly shows that there is a pathway of brine feeding Blood Falls. It appears from underneath the glacier and then extends horizontally more than 300 feet to Blood Falls. 

 A research team led by the University of Alaska Fairbanks and Colorado College has solved a century-old mystery involving a famous red waterfall in Antarctica. New evidence links Blood Falls to a large source of salty water that may have been trapped under Taylor Glacier for more than 1 million years. 
 
 The team's study, published in the Journal of Glaciology, describes the brine's 300-foot path from beneath Taylor Glacier to the waterfall. This path has been a mystery since geoscientist Griffith Taylor discovered Blood Falls in 1911. 
 
 Lead author Jessica Badgeley, then an undergraduate student at Colorado College, worked with University of Alaska Fairbanks glaciologist Erin Pettit and her research team to understand this unique feature. They used a type of radar to detect the brine feeding Blood Falls. 
 
 "The salts in the brine made this discovery possible by amplifying contrast with the fresh glacier ice," Badgeley said. 
 
 Blood Falls is famous for its sporadic releases of iron-rich salty water. The brine turns red when the iron contacts air. 
 
 The team tracked the brine with radio-echo sounding, a radar method that uses two antenna -- one to transmit electrical pulses and one to receive the signals. 
 
 "We moved the antennae around the glacier in grid-like patterns so that we could 'see' what was underneath us inside the ice, kind of like a bat uses echolocation to 'see' things around it," said co-author Christina Carr, a doctoral student at UAF. 
 
 Pettit said the researchers made another significant discovery - that liquid water can persist inside an extremely cold glacier. Scientists previously thought this was nearly impossible, but Pettit said the freezing process explains how water can flow in a cold glacier. 
 
 "While it sounds counterintuitive, water releases heat as it freezes, and that heat warms the surrounding colder ice," she said. The heat and the lower freezing temperature of salty water make liquid movement possible. "Taylor Glacier is now the coldest known glacier to have persistently flowing water." 
 
 Pettit said she enlisted Badgeley as an undergraduate student to help with the overall mission of understanding the hydrological plumbing of cold-based glaciers. 
 
 "Jessica's work is a perfect example of the high level of work undergraduate students can do when you give them a challenge and set the expectations high," she said. 
 
 ### 
 
 The National Science Foundation sponsored the research.
– The only thing that has moved slower than Taylor Glacier is progress on solving a 100-year-old mystery about the famous red waterfall nearby—until now. Since 1911, when a scientist first stumbled across Antarctica's Blood Falls, researchers have been scratching their heads about a flow of salty water leading from the glacier to what Atlas Obscura refers to as the "five-story, blood-red waterfall." But a study published in the Journal of Glaciology may have unearthed what's behind this "englacial hydrologic system" fueling the falls. The direct reason for why the water is red isn't what's been perplexing us: A press release explains that the water plummeting over the side is filled with iron, which causes the brine to turn red when it makes contact with oxygen. It's where this brine is coming from, however, that has remained an unknown. That is, until scientists from the University of Alaska Fairbanks and Colorado College set to work with radar gear and found evidence of lots of salty water buried beneath the glacier, perhaps for up to 1 million years. Much like the echolocation used by bats, the technique the scientists used to send and receive electrical signals in "grid-like patterns" through the glacier's ice led them to a find previously thought impossible: flowing liquid water existing in a frozen glacier. Co-author Erin Pettit explains that "water releases heat as it freezes," which melts surrounding ice and lets the salty water (with a lower freezing temperature) flow. The discovery now opens the doors to "understanding the role of liquid water—salty or fresh—in other extremely cold glaciers or permafrost environments," co-author Jessica Badgeley adds, per a Colorado College press release. (This Yosemite "firefall" appears once a year.)