Geologists Suspect That the Stone Mounds in Padang Pariaman, West Sumatra are Thick Columns

Residents saw rocks that were thought to be bulky columns in Lubuk Alung District, Padang Pariaman Regency, West Sumatra, Thursday (12/10/2023). (ANTARA/Muhammad Zulfikar)

WEST SUMATRA - Geologist and volcanologist Ade Edward suspects that the rock mounds found by residents in Lubuk Alung District, Padang Pariaman Regency, West Sumatra Province (Sumbar), are solid columns.

"We have actually been looking for this for a long time. This sturdy column is one of the items we are looking for," he said in Padang Pariaman, West Sumatra, Thursday, October 12, as reported by Antara.

Based on the results of physical observations in the field, he said, the rocks in the mound found in Lubuk Alung were a type of basaltic andesite rock or between andesite and basaltic rock.

He added that andesite rock is light gray in color and basaltic rock is more gray or close to black.

Ade explained that the rocks were formed due to the process of freezing magma below the earth's surface which then slipped through cracks or fractures.

"The magma is under pressure and seeps into the cracks of the rock, causing it to freeze," he said.

In the process of changing mass from liquid to solid, he continued, shrinkage and hardening occur.

"That's when a phenomenon occurred that formed columns called columnar joints," he said.

Ade revealed that the age of the rocks which are thought to be solid columns in Lubuk Alung is probably between 40-60 million years.

According to him, research and assessment is needed to determine the age of the rocks.

Ade said that sturdy columns can also be found in the Anai Valley waterfall area, Tanah Datar Regency, West Sumatra.

According to him, the rock structure in the columnar joints in the Anai Valley is much neater than the rock structure in the mounds found in the Padang Pariaman area.