Program Studi Teknik Geologi

"Institut Teknologi Sumatera"


Blog D. G. Harbowo

Danni Gathot Harbowo Geologi Institut Teknologi Sumatera

Hi there! How are you today?

Howdy, my name is Danni G. Harbowo. I’m a lecture in Department of Geology, Institut Teknologi Sumatera. How nice to see you. In this page, I’ll present you my activity which related with earth science. My focus study is paleontology, sedimentology, and volcanology. We can share and discuss about what I was discovered in my field observation. I’m surely glad with that. So let’s take a look and see you soon.





Danni Gathot Harbowo, Department of Geology, Institut Teknologi Sumatera

Danni Gathot Harbowo Krakatau

Anak Krakatoa, the Sleeping Giant

Between Java and Sumatra islands there was a sleeping giant. There stand alone in the middle of the sea and waiting to awake and make a loud noise. 1883 is the year when she was awake before take a long sleep. Take a huge eruption and make a wide destruction, all people around the world must know who she is. You’re right, Krakatoa. It is the name of the symbol of natural destruction in the modern age, the most dangerous volcano from the past time. Killed almost ten thousand people and make a widespread catastrophe. In that time, Indonesia still dominates with Netherlands colonies and there a no many documented records except from Netherlands government.

Today Krakatoa still active but not given a signify dangerous. But, Krakatoa has a several threat still hidden for our future, are she will erupt again? How large is it? We still can see the lava and the volcanic ash erupted from that volcano, it indicated that the volcano still had magma in high pressure.

Otherwise, in the land of Krakatoa, today we can see the vegetation grows around island margin. Their seeds come from main island, Java and Sumatera. It’s very surprising that succession has been happened in Krakatoa. We can categorize it as primary succession, the environment recovery step after totally destruction from catastrophic event.

To take a look more detail, you should go there. Good luck.

Danni Gathot Harbowo Institut Teknologi Sumatera

Limestone in Rajamandala

There is no such questionable thing if we observer the word of limestone. Lime and stone, two words that very different and merge into one word. Lime is mean to fruit which very sour or acid, stone mean a rock. So why is it called limestone? Limestone is the carbonate rock, which is it contain much carbonate ion (CO3). Mostly it bonded with calcium or magnesium, forming mineral Calcite if bonded with calcium. Calcite always reacts with very acid liquid, and produce Hydrogen gas (H2). So, if you have a limestone and exposed to the acid liquid it will react and producing bubbling gases. Because of that, we named that rock limestone.

Rajamandala is the formation which dominated with limestone. It located in West Java, very near from Bandung, the province’s capital city. Limestone commonly generate from reef environment which has many corals, mollusk, and echinodermata. They are invertebrate animal which has shell and main body structure from carbonate mineral. Accumulated in marine environment and deposited time by time from Miocene forming rock. So if you observe more closely, you easily to find fossils, the remains of organism that were turn into rock. Very interesting to know, and you must want to take home for your own souvenirs.


So, let’s being fossil hunter, hope you’ll have a best shot.

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