− | The past decade has seen a renewed interest in surface geochemical exploration. Coupled with developments in analytical and interpretive methods, this interest has produced a new body of data and insights, many of which are summarized in AAPG Memoir 66.<ref name=ch18r39>Schumacher, D., 1996, Hydrocarbon-induced alteration of soils and sediments, in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: AAPG Memoir 66, p. 71–89.</ref> There is now consensus with the following points: | + | The past decade has seen a renewed interest in surface geochemical exploration. Coupled with developments in analytical and interpretive methods, this interest has produced a new body of data and insights, many of which are summarized in AAPG Memoir 66.<ref name=ch18r39>Schumacher, D., 1996, [http://archives.datapages.com/data/specpubs/memoir66/06/0071.htm Hydrocarbon-induced alteration of soils and sediments], in Schumacher, D., Abrams, M., A., eds., Hydrocarbon Migration and Its Near-Surface Expression: [http://store.aapg.org/detail.aspx?id=75 AAPG Memoir 66], p. 71–89.</ref> There is now consensus with the following points: |