Dorian/Aeolian Gapped Scales and Hybrids
Link to Ionian, Mixolydian, Dorian and Aeolian: Samples and Examples of the 4 Main Musical Scales in Celtic, Anglo-American and English Folk Songs [[1]]
The Aeolian scale is the same as the Dorian scale except that the sixth note is flattened by a semitone. To convert a Dorian to an Aeolian key signature, add a flat to, or remove a sharp from, it. Likewise, to convert an Aeolian to a Dorian key signature, remove a flat from, or add a sharp to, it. The Dorian and Aeolian scales are thus quite similar to each other, and there are quite a few Dorian/Aeolian gapped scales and quite a few Dorian/Aeolian hybrids. Here are some examples.
04 Robin Hood and the Tanner (Cecil J. Sharp, 1916, One Hundred English Folk Songs)
Link: http://folkopedia.efdss.org/wiki/04_Robin_Hood_and_the_Tanner
Tune Analysis: D Dorian key signature but one of the Bs (6th) is flattened to produce a Dorian/Aeolian hybrid. Heptatonic, Mainly Authentic but there is a C that dips below the keynote.
06 Lord Bateman (Cecil J. Sharp, 1916, One Hundred English Folk Songs)
Link: http://folkopedia.efdss.org/wiki/06_Lord_Bateman
Tune Analysis: G Aeolian key signature but no E (6th). Hexatonic G Dorian/G Aeolian gapped scale, Plagal.
09 Geordie (Cecil J. Sharp, 1916, One Hundred English Folk Songs)
Link: http://folkopedia.efdss.org/wiki/09_Geordie
Tune Analysis: A Aeolian key signature but no F (6th). Hexatonic G Dorian/G Aeolian gapped scale, Plagal.
As I Roamed Out (GB/6a/5)
Link: https://www.vwml.org/search?q=GB/6a/5&is=1#
Tune Analysis: D Aeolian key signature but some of the Bbs (6ths) are naturalised to produce a Dorian/Aeolian hybrid. Heptatonic, Plagal.
Basket of Eggs Version 2 of 2 (GB/6a/18)
Link: https://www.vwml.org/search?q=GB/6a/18&is=1#
Tune Analysis: The key signature is E Aeolian but two of the Cs are sharpened to produce a Dorian/Aeolian hybrid. Heptatonic, Authentic.
Cupid the Ploughboy Version 1 of 3 (GB/6a/59)
Link: https://www.vwml.org/search?q=GB/6a/59&is=1
Tune Analysis: G Aeolian key signature but scale is Hexatonic with no Es (6th). If the Es are presumed to be natural the scale is Dorian, if flattened Aeolian. Plagal.