GeoTime - Tebogo Makhubela
Dr Tebobo Makhubela: Geologist; Senior Lecturer in Geology, University of Johannesburg #BurialDating #EarthSurface #Useries #CosmogenicNuclides #Geology #Geochronology
His Research: How do you determine how old a rock or fossil is? That’s really what my research is all about. We know that usually a rock layer that is above another rock layer is younger but how do you know if it’s 10,000 years old or 100 million years old? My research group measures isotopes of different atoms to determine the age of geological and paleontological deposits and the fossils that are in them.
An isotope is a different form of an atom. Carbon atoms, for example can be carbon-12, carbon-13, or carbon-14. The difference is in the number of neutrons in that atom. Carbon-14 is formed in the atmosphere by interactions with cosmic rays (no really!). Those carbon-14 atoms get incorporated into plants and animals - carbon is the building block of all life. Once a plant or animal stops living it stops bringing in new carbon. This is now when it gets interesting.
Carbon-14 is radioactive (don’t worry, you even have some in your body, but very low amounts) and it becomes the non-radioactive carbon-12 over time. So living organisms have relatively high carbon-14 and then once they die they have less and less. If you think about this, it’s like a clock. The amount of Carbon-14 ticks down over time. We can measure the amount of carbon-14 in a sample and then calculate approximately when it died. This is called carbon dating and can be used for dating things between 100 and 50,000 years old. There are similar methods for dating fossils and rocks going back millions of years.
We use these techniques to date fossils and to understand the changes on the Earth's surface - this is called geomorphology (geo=Earth, morphology=shape). Our most important work involves developing new techniques for dating fossils found at the Cradle of Humankind in an effort to understand human evolution.
Watch Tebogo in the #105site excavation site with Prof Lee Berger
His Heroes: My grandmother, Marie Curie (two time Nobel Prize winner), Thabo Mbeki and Bear Grylls. What a combo! Watch Tebogo tell how his grandmother helped him get curious about rocks. The littlest question can make such a difference.
His Top Tip: The best time to start was yesterday, the second best is today. Just start, you’ll find your way.
That Sciene Spark: My curiosity about volcanoes, other Earth processes, and the different rocks around me (see the story with his grandmother above) led me to study geology. I followed that interest through university and graduate school and today I am a geologist studying the geochemistry of different Earth surface environments.
What do you need to succeed (ranked in order)? Curiosity, hard work, communication and creativity
What else do you need? Critical thinking and passion!
His Superpowers! Age determination using isotopes. Quantifying landscape changes.
His Scientific Strengths: Doing analytical work in the laboratory, initiating collaborations, and training postgraduate students
Connect: Twitter @tebogorium_119
Funda ngesiZulu
UDkt Tebobo Makhubela: Isazi sokuma komhlaba; Umfundisi Omkhulu weGeology, University of Johannesburg #BurialDating #EarthSurface #Useries #CosmogenicNuclides #Geology #Geochronology
Ucwaningo Lwakhe: Wazi kanjani ukuthi itshe itshe lidala kangakanani noma izinsalela zamathambo ukuthi zindala kangakanani? Ucwaningo lwami lungalokho. Siyazi ukuthi ngokuvamile uhla lwamadwala olungaphezu kwelinye idwala luncane kodwa wazi kanjani ukuthi luneminyaka eyi-10,000 ubudala noma iminyaka eyizigidi eziyi-100 ubudala? Iqembu lami lokucwaninga lilinganisa ama-isotopes ama-athomu ahlukahlukene ukuze linqume ubudala bezindawo zokuma komhlaba nezama-paleontological kanye nezinsalela ezikuzo.
I-isotope iwuhlobo oluhlukile lwe-athomu. Ama-athomu ekhabhoni, isibonelo, angaba yi-carbon-12, i-carbon-13, noma i-carbon-14. Umehluko usenani lama-neutron kuleyo athomu. I-Carbon-14 yakhiwa emkhathini ngokusebenzisana nemisebe ye-cosmic (okwangempela!). Lawo ma-athomu e-carbon-14 ahlanganiswa ezitshalweni nasezilwaneni - ikhabhoni iyisakhiwo sayo yonke impilo. Uma isitshalo noma isilwane sesiyeke ukuphila siyayeka ukuletha ikhabhoni entsha. Okuthakalisayo kuqala lana ke!
ICarbon-14 i-radioactive (ungakhathazeki, unokuthile emzimbeni wakho, kodwa amanani aphansi kakhulu) futhi iba yi-carbon-12 engeyona imisebe ngokuhamba kwesikhathi. Ngakho-ke izinto eziphilayo zine-Carbon-14 ephakeme uma kuqhathaniswa bese kuthi uma sezifile ziya ngokwehla. Mawucabanga kahle ngalokhi, kucishe kufane newashi! Singakala inani le-carbon-14 kusampula bese sibala cishe ukuthi ifile nini. Lokhu kubizwa nge-carbon dating futhi kungasetshenziswa ukuthola izinto phakathi kweminyaka eyi-100 ne-50,000 ubudala. Kunezindlela ezicishe zifane zokuthola lokhu.
Sisebenzisa lezi zindlela ukuze sithole izinsuku zezinsalela kanye nokuqonda izinguquko ebusweni bomhlaba - lokhu kubizwa ngokuthi i-geomorphology (geo=umhlaba, morphology=ukwabelana kwawo). Umsebenzi wethu obaluleke kakhulu uholela ukuthuthukisa amasu amasha okuqophisama nezinsalela ezitholakala ku-Cradle of Humankind emzamweni zokuqonda ukuguquka kwabantu.
Amaqhawe Akhe: Ugogo wami, uMarie Curie (owine uMklomelo kaNobel kwaze kwaba kabili), uThabo Mbeki kanye noBear Grylls. Buka uTebogo elandisa ukuthi ugogo wakhe wamsiza kanjani ukuba athande amatshe. Umbuzo omncane kakhulu ungenza umehluko omkhulu.
Ithiphu Yakhe Enkulu: Isikhathi esihle sokuqala bekuyizolo, esesibili esihle kakhulu inamuhla. Vele uqale, uzothola indlela yakho!
That Science Spark: Ilukuluku lami ngezintaba-mlilo, ezinye izinqubo zoMhlaba, namadwala ahlukene aseduze kwami (bona indaba nogogo wakhe ngenhla) kwangiholela ekufundeni isayensi yokwakheka komhlaba. Ngalandela leyo ntshisekelo ngenyuvesi kanye nesikole seziqu futhi namuhla ngiyisazi sokuma komhlaba esifunda i-geochemistry yezindawo ezihlukene zomhlaba.
Yini oyidingayo ukuze uphumelele (ngokulandelana kwakho)? Ilukuluku, ukusebenza kanzima, ukuxhumana kanye nobuhlakani.
Yini enye oyidingayo? Ukucabanga okubucayi nothando!
Amandla Akhe Amakhulu! Ububheka iminyaka esebenzisa ama-isotopes. Ukulinganisa izinguquko ze-landscape.
Amandla Akhe Esayensi: Ukwenza umsebenzi wokuhlaziya elabhorethri, ukuqala ukusebenzisana kanye nokuqeqesha abafundi beziqu eziphezulu zasenyuvesi.
Xhumana no-GeoTime: Twitter @tebogorium_119