By PETER KEEPNEWSAUG. 31, 2014  Glenn Cornick, the original bassist in the popular British rock group Jethro Tull in the late 1960s, died on Thursday at his home in Hilo, Hawaii. He was 67.  His death was announced on the band’s website. His family said the cause was congestive heart failure.  The focal point of Jethro Tull, which was formed in late 1967 and remained active into this year, was always Ian Anderson, who in addition to being the lead singer and principal songwriter is a charismatic performer and one of the few rock musicians to play flute. But the contributions of Mr. Cornick and the band’s other two members — for most of his three-year tenure he played alongside the guitarist Martin Barre and the drummer Clive Bunker — did not go unnoticed.  The group typically “creates a deep, rumbling bass and guitar line and paints a breathy flute ribbon upon it,” Mike Jahn wrote in a 1969 New York Times review of Jethro Tull’s performance at the Fillmore East. “It maintains this through moments of loud, typically British rock bashing, and occasional passages of relatively quiet, inauspicious jazz.”  Like many other British rock bands of its era, Jethro Tull, whimsically named after an 18th-century British agriculturist, started out primarily playing the blues. But the group did not achieve widespread fame until its sound developed into something more ambitious and uncategorizable, incorporating elements of jazz, folk and even classical music.  In a 2011 interview with the magazine It’s Psychedelic, Baby, Mr. Cornick recalled that he and his bandmates had been surprised by the reaction to Jethro Tull’s second album, “Stand Up.” “We still thought we were a blues band,” he said. “You don’t consciously change the direction of your music. It just happens naturally, so we were all shocked when the album was released and people said, ‘Oh, they’re not playing blues anymore.’ ”  Glenn Douglas Barnard Cornick was born in Barrow-in-Furness, Cumbria, England, on April 23, 1947. He began playing bass in his teens and first worked with Mr. Anderson in Blackpool in a band that eventually evolved into Jethro Tull. Mr. Cornick played on the band’s first three albums, “This Was” (1968), “Stand Up” (1969) and “Benefit” (1970), and on its first tours.  He left shortly before the band recorded its celebrated album “Aqualung” and was replaced by Jeffrey Hammond. He later formed the band Wild Turkey and was a member of Paris, a group that also included the former Fleetwood Mac singer and guitarist Bob Welch.  Mr. Cornick is survived by his wife, Brigitte Martinez-Cornick; a daughter, Molly Cornick; and two sons, Drew and Alex.  In a statement on the Jethro Tull website, Mr. Anderson praised Mr. Cornick as someone who “brought to the early stage performances of Tull a lively bravado both as a personality and a musician.”  A version of this article appears in print on September 1, 2014, on page A18 of the New York edition with the headline: Glenn Cornick, 67, Original Bassist in Jethro Tull. Order Reprints|Today's Paper|Subscribe
Mr. Cornick was a founding member of a British band that began with a blues sound and expanded steadily in scope.