Collection place
- Mackie Mound, Linn County, Western Oregon6 objects
- Mad River slough, Humboldt County, California14 objects
- Madeline Plains, Lassen County, California319 objects
- Madera County, California84 objects
- Madera Municipality, Chihuahua, Mexico1 objects
- Madhya Pradesh, India5 objects
- Maharashtra State, India5 objects
- Mahoning County, Ohio8 objects
- Maine19 objects
- Malawi2 objects
- Malay Peninsula, Southeast Asia1 objects
- Malaysia1 objects
- Mali31 objects
- Malibu, Santa Monica Mountains, Los Angeles County4 objects
- Malpais, Apatzingán, Apatzingan1 objects
- Mammoth Lakes, Mono County, California1 objects
- Manakee, Lake County, California2 objects
- Mandla, Narmada valley, Madhya Pradesh3 objects
- Manteca Canyon area, Tecate municipality, Baja California9 objects
- Manteca Canyon, Tecate municipality, Baja California9 objects