Page "Amazon River" Paragraph 4

Several geological factors have played a vital role in the formation and existence of these subterranean water bodies.

The underground ocean, discovered in 2007, has been formed when the plate carrying the Pacific Ocean bottom gets dragged and ends up under the continental plate.

Water at such depths would normally escape upwards but the unusual conditions that exist along the eastern Pacific Rim allow the moisture to remain intact.

In the case of the Hamza, the porous and permeable sedimentary rocks behave as conduits for the water to sink to greater depths.

East-west trending faults and the karst topography present along the northern border of the Amazon basin may have some role in supplying water to the river.

If the impermeable rocks stop the vertical flow, the west to east gradient of the topography directs it to flow towards the Atlantic Ocean.

Unlike the Hamza, the 153 km-long underground river in Mexico's Yucatán Peninsula and the 8. 2 km-long Cabayugan River in the Puerto Princesa Subterranean River National Park in the Philippines have come into being thanks to the karst topography.

Water in these places drills its way downward by dissolving the carbonate rock to form an extensive underground river system.