Possible Clues:

• Rough road surface
• Little bits of 24 across - enough to bury fifty there
• How serious to get fifty in little bits!
• Gee! That composer comes in bits
• Coarse sand with small stones used for roads, driveways etc
• Driveway cover, perhaps
• Type of driveway
• Gee, there are many hard bits with the composer!
• Little rock?
• Small stones on paths