Jan. 12, 10 a.m.-1 p.m., Patapsco Valley State Park, Avalon area, 5120 South St., Halethorpe, Baltimore County. Meet at the Lost Lake parking lot to begin your trip and make your own pace along the Grist Mill Trail. A ranger will be at the trail entrance. For all ages. Water will be available. Call 410-461-5005 to sign up or for more information. No fee. Donations welcome.