Pupils' chances of being able to study for a geography GCSE depend on where they live and the kind of school they go to, according to new research.
Geography remains among the top ten most popular GCSE subjects, but a Birmingham University study has uncovered significant discrepancies in entry levels.
School type makes a difference, but so does geography itself, with the numbers of pupils taking the subject at GCSE lowest in inner-city schools and highest in suburban or rural areas.
Paul Weeden, the author of the report, argues a divide is developing, with a vocational curriculum for the poor and an academic curriculum for the rich.
"The unequal entry numbers appear to come partly from the pressure of league tables," the lecturer in geography education said. "To boost school performance scores, some low-performing urban schools have encouraged many students to take vocational qualifications that give the equivalent of four GCSEs but require less timetable time."
The Birmingham study, being presented at the Royal Geographical Society's conference in London this week, follows evidence of particularly low entry levels for geography among academies.
Last year, think-tank Civitas asked all existing academies to provide details of the exams they entered pupils for.
Among the 16 academies prepared to release the information, the highest proportion of a cohort entered for geography GCSE was 38 per cent. One academy had no entries in the subject at all out of a cohort of 147.
The research found academies were ignoring academic GCSEs in favour of qualifications such as OCR's level 2 national certificate in travel and tourism in which pupils can learn about the responsibilities of an airline cabin crew.
This week, Dr Weeden said that urban local authorities were much more likely to have low geography GCSE entries than those in rural areas. There was an even greater disparity when the authorities were divided according to levels of deprivation.
"High-achieving schools seem to be under less pressure to change their traditional academic curriculum," the Birmingham University academic said.
"Entries were highest in independent, grammar and high-achieving comprehensive schools, and my findings suggest there is a danger of re-introducing the historical divide between a vocational curriculum for the poor and an academic curriculum for the rich."
Numbers of geography GCSE entries have been in almost continuous decline for the past 14 years. This summer there were 194,599 entries, which left the subject at number eight in the popularity table.
Rita Gardner, Royal Geographical Society director, said: "Equal access to choose geography as a GCSE subject is essential when you consider how important it is for young people to understand the world.
"They will have the job of managing it for the benefit of future generations, and geography will help them to understand their own country better and the pressures on the world's resources, environments and populations."