GEL 158 was awarded to Petratherm Ltd on 2/1/2004 for an initial term of 5 years. Original surface area of the licence was 499km2 .The licence was located in the northern part of the Gawler Craton some 90km north of Roxby Downs. The initial interest in the area was investigation of the possibility of a Radiogenic Iron Oxide (RIO) target being present with a view to possible geothermal heat extraction. The Ferguson Hill MT Survey was recorded in late 2007 over a 14 km long traverse oriented NE-SW. Interpretation of the data revealed an interpreted cover of perhaps 1800-2000m on top of basement. This is less than the proposed 3000m depth required to have a viable geothermal prospect. The licence was subsequently surrendered with no further work completed on 3/11/2008.