Taña Dalglish Jun 3, 2008:

http://www.das.psu.edu/user/publications/pdf/ub038.pdf
Riding Arena Footing Materials
HORSE FACILITIES 6
C O L L E G E O F A G R I C U L T U R A L S C I E N C E S
A G R I C U L T U R A L R E S E A R C H A N D C O O P E R A T I V E E X T E N S I O N
Table of Contents
Riding Arena Surface ................................. 1
Common Footing Materials ........................ 2
Challenging Footing Materials ................... 4
Locally Available Materials ........................ 4
Characterizing Footing Materials .............. 4

Taña Dalglish Jun 3, 2008:

spring_moon: To the best of my knowledge the word "footing" is not a type of horseshoe, but rather refers to the surface, for example in an arena.