An Australian creationist has received permission to collect rocks from the Grand Canyon in an attempt to prove the occurance of a great biblical flood - thanks in part a recent executive order from Donald Trump.

The National Parks service recently approved an application from Andrew Snelling, a certified geologist and evangelical Christian, which will allow him to collect “50 or 60” fist-sized rocks from the Grand Canyon.

Mr Snelling said the samples will serve his work of "investigating geological phenomena from the perspective of one who believes in the truth of the Old and the New Testaments”.

The National Parks Service had initially declined the application, claiming his application lacked scientific merit.

But the scientist sued for religious discrimination, citing a recent executive order from Mr Trump. The order directs federal agencies to “respect and protect the freedom of persons and organisations to engage in religious and political speech”.

Mr Snelling is a young-Earth creationist – a small religious subset that believes the earth was created by God only a few thousand years ago.

The scientist believes the Grand Canyon is not a result of billions of years of erosion, but of a “catastrophic erosion” event after Noah’s flood.

In considering Mr Snelling’s proposal, the Park Service consulted three mainstream geologists. All three said his work was not scientifically valid and one pointed out that the rocks could also be found outside the canyon.

"My overall conclusion is that Dr. Snelling has no scientific track record and no scientific affiliation since 1982," wrote Karl Karlstrom, a geologist at the University of New Mexico.

The Parks Service also noted that Mr Snelling's proposed sampling method – a hammer and chisel – would "permanently visibly mar the geological structures themselves".

But lawyers for the Alliance Defending Freedom (ADF), a Christian legal advocacy group who filed the lawsuit on Mr Snelling’s behalf, maintained that this was a case of religious discrimination.

National parks Show all 9 1 /9 National parks National parks Vew of the Half Dome monolith from Glacier Point at the Yosemite National Park MARK RALSTON/AFP/Getty Images National parks View of Delicate Arch sandstone rock formation at Arches National Park, near Moab, Utah, 1960s. (Photo by Harvey Meston/Getty Images) Getty Images National parks A view of Denali, formerly known as Mt. McKinley, on September 1, 2015 in Denali National Park, Alaska Lance King/Getty Images National parks The Lower Basins Zone is outlined by the white rim edge as seen from the Murphy Campsite on the White Rim Trail on October 26, 2007 in Canyonlands National Park, Utah Doug Pensinger/Getty Images National parks A Perseid meteor streaks across the sky above the hoodoos named Thor's Hammer (L) and the Three Sisters (R) early on August 13, 2016 in Bryce Canyon National Park, Utah Ethan Miller/Getty Images National parks Visitors explore The Narrows along the Virgin River Sean Gallup/Getty Images National parks GRAND CANYON, AZ - MARCH 20: People take the first official walk on the Skywalk, billed as the first-ever cantilever-shaped glass walkway extending 70 feet from the western Grand Canyon's rim more than 4,000 feet above the Colorado River, on March 20, 2007 on the Hualapai Reservation at Grand Canyon, Arizona. The building of the Skywalk on Hualapai Indian tribal land 90 miles downstream from Grand Canyon National Park has stirred controversy with some tribal elders and environmentalists who have condemned it as a desecration of a sacred American landscape. The $40 million glass and steel platform will open to the public on March 28 when visitors will be allowed to take the lofty walk at a cost of $25 per person plus the cost of a Grand Canyon West entrance package, a total of about $75. (Photo by David McNew/Getty Images) Getty National parks The Grand Prismatic Spring, the largest in the United States and third largest in the world, is seen in Yellowstone National Park, Wyoming, June 22, 2011 REUTERS/Jim Urquhart National parks Lava flows into the ocean from Kilauea Volcano at Volcanoes National Park near Volcano, Hawaii June 6, 2004 Marco Garcia/Getty Images

“This case perfectly illustrates why President Trump had to order executive agencies to affirm religious freedom, because Park officials specifically targeted Dr. Snelling’s religious faith as the reason to stop his research,” ADF lawyer Gary McCaleb said.

The Parks Service has now agreed to let Mr Snelling proceed with his research, so long as he meets with “experienced staff” to discuss sampling locations and "appropriate sampling methodology".