Wyoming Geology: A World-Class Wonderland

Beautifully polished ammonite fossil pair from the Mahajanga Basin, Northwest Madagascar (Cretaceous, ~110–120 million years ago). Each half measures 4.5” across. This specimen preserves a complete coiled form with excellent internal definition, where the chamber walls (septa) are expressed in bright white calcite, sharply outlining the internal buoyancy architecture. The back side of the coil clearly exposes the sutures, the intricate folded junctions
where each septum met the outer shell wall, recording both growth progression and structural reinforcement of the shell. Patches of original nacreous shell material (mother-of-pearl aragonite) remain visible in places, adding subtle iridescent flashes that contrast with the calcite-replaced internal structure and highlight the original shell composition. 

Raffle rules:

• Must be present to win.
• Drawing will be at 6:00 pm in the library auditorium.
• Members receive one free ticket. One ticket per Membership.
• Members may purchase additional tickets for $5 each.
• You can buy/renew your 2026 Membership that night via cash, check, or Venmo (no IOU’s).
• Membership costs $20 individual, $35 family, $50 for a sustaining membership and $750 for a lifetime membership.
• GJH board members are not eligible to participate.