Question: Gregory Blaxland is credited with what achievement?

Context paragraphs:
Division of Blaxland: The Division of Blaxland is an Australian electoral division in the state of New South Wales.  The division was created in 1949 and is named after Gregory Blaxland, a farmer and an early Australian explorer of the Blue Mountains in New South Wales.

Greg Butler (visual effects supervisor): Gregory S. Butler (August 18, 1971, Suffield, Connecticut) is a visual effects supervisor.  He graduated from Suffield High School in 1989 and afterwards entered Hampshire College.  Despite his initial plans to study history, a work-study job with the audiovisual equipment in the library made him interested in film production.  Butler graduated in 1993 with a major in film, television and theater design.  Afterwards he moved to California to work for Industrial Light and Magic for 9 months, where after intern work he managed to become an assistant in the effects department, starting with assistant credits in "The Mask" and "Forrest Gump".  Following a job at Rocket Science Games until the company's bankruptcy in 1996, Butler went to Tippett Studio and did effects work in "Starship Troopers" and "My Favorite Martian", rising up to a technical director job, and Cinesite for "Practical Magic".  While reluctant at the requirement of moving to New Zealand, Butler was convinced by his writer-actor brother Jared to jump at the opportunity of working for Weta Digital in "The Lord of the Rings".  His biggest achievement was working in the creation of Gollum.  Butler also worked as a computer graphics supervisor on "I, Robot" before an invitation to work as an effects supervisor for the Moving Picture Company, in London.  He continues on MPC, but is now on the Vancouver office.  On January 24, 2012, he was nominated for an Academy Award for "".

1813 crossing of the Blue Mountains: The 1813 crossing of the Blue Mountains was the expedition led by Gregory Blaxland, William Lawson and William Charles Wentworth, which became the first successful crossing of the Blue Mountains in New South Wales by European settlers.  The crossing enabled the settlers to access and use the land west of the mountains for farming, and made possible the establishment of Australia's first inland settlement at Bathurst.

David McClelland: David Clarence McClelland (May 20, 1917 – March 27, 1998) was an American psychologist, noted for his work on motivation Need Theory.  He published a number of works during the 1950s and the 1990s and developed new scoring systems for the Thematic Apperception Test (TAT) and its descendants.  McClelland is credited with developing the Achievement Motivation Theory commonly referred to as need achievement or "n"-achievement theory.  A "Review of General Psychology" survey, published in 2002, ranked McClelland as the 15th most cited psychologist of the 20th century.

William Lawson (explorer): William Lawson, MLC (2 June 1774 – 16 June 1850) was an English born explorer, land owner, grazier and politician who migrated to Sydney, New South Wales in 1800.  With Gregory Blaxland and William Wentworth, he participated in the first successful crossing of the Blue Mountains by European settlers.

David Gregory (physician): David Gregory (20 December 1625 – 1720) was a Scottish physician and inventor.  His surname is sometimes spelt as Gregorie, the original Scottish spelling.  He inherited Kinnairdy Castle in 1664.  Three of his twenty-nine children became mathematics professors.  He is credited with inventing a military cannon that Isaac Newton described as "being destructive to the human species".  Copies and details of the model no longer exist.  Gregory's use of a barometer to predict farming-related weather conditions led him to be accused of witchcraft by Presbyterian ministers from Aberdeen, although he was never convicted.

Gregory Blaxland: Gregory Blaxland (17 June 1778 – 1 January 1853) was an English pioneer farmer and explorer in Australia, noted especially for initiating and co-leading the first successful crossing of the Blue Mountains by European settlers.

Explorers tree: The Explorers Tree is a tree on which Gregory Blaxland, William Lawson and William Charles Wentworth, the explorers who achieved the first known successful crossing of the Blue Mountains of New South Wales by European settlers, carved their initials in 1813.

Gregory Dark: Gregory Dark (born Gregory Hippolyte Brown on July 12, 1957 in Los Angeles) is an American film director, film producer, music video director, and screenwriter.  Dark is one of the few adult filmmakers to successfully transition into mainstream Hollywood film-making.  He has also been credited as Alexander Hippolyte, as Gregory Brown, and as The Dark Brothers.

1813 in Australia: 1813 in Australia featured a number of important developments.  Gregory Blaxland, William Lawson and William Charles Wentworth crossed the Blue Mountains which opened up the interior of New South Wales for European settlement.  John and Elizabeth Macarthur sent the first wool exports from their properties.

Supporting paragraphs: Gregory Blaxland 1813 crossing of the Blue Mountains
Answer: 1813 crossing of the Blue Mountains