A Field Guide to the Identification and Collection of Rocks Across North Dakota North Dakota’s landscape reflects a long history of ancient seas, swampy lowlands, and powerful glaciers that shaped the northern Great Plains. While the state lacks the mountain exposures found farther west, its badlands, river valleys, and glacial deposits preserve a wide variety of rocks, fossils, and transported minerals that reward careful observation in the field. In western North Dakota , the rugged terrain of the Little Missouri River badlands exposes layers of sandstone, clay, and lignite coal belonging to the Paleocene Fort Union Formation. These sediments formed in low, swampy environments after the retreat of the Western Interior Seaway. As the soft rock weathers, it releases fossil plant material, ironstone concretions, and pieces of petrified wood that commonly accumulate along gullies and small streambeds. The same formations occasionally preserve vertebrate fossils, reflecting the rich ecosystems that once occupied these ancient floodplains. Petrified wood is among the most recognizable materials in the badlands. Silicified logs and fragments weather from the surrounding sediments and are often found scattered across hillsides or concentrated in gravel washes after seasonal storms. Many specimens show well-preserved grain patterns and a range of natural colors created by mineral replacement during fossilization. Across central and eastern North Dakota , the geology changes significantly. Thick layers of glacial sediment cover much of the region, deposited during the advance and retreat of continental ice sheets during the last Ice Age. These glaciers carried rock from far to the north, scattering a diverse mix of granite, basalt, quartzite, and other resistant stones across the plains. Because of this glacial transport, collectors often find rock types that originated hundreds of miles away. Gravel pits, cultivated fields, and streambeds frequently contain rounded cobbles of Canadian granite, banded gneiss, and quartzite, along with occasional agates and other durable minerals carried southward by the ice. Rivers continue to shape these deposits today. The Missouri River and its tributaries cut through glacial sediments and weathered badland formations, concentrating fossils, concretions, petrified wood, and transported stones along gravel bars and cutbanks where they can be examined in the field. This guide is written for collectors and field observers seeking a practical understanding of North Dakota’s rocks, minerals, and fossils. Emphasis is placed on recognizing specimens in natural settings how they occur in badland exposures, how they weather from sedimentary formations, and where they tend to accumulate in river gravels and glacial deposits. Regional chapters describe collecting opportunities across the state, including the fossil-bearing badlands of the west and the glacial landscapes of the central and eastern plains. Each section outlines the geologic setting, common materials, and practical considerations for exploring these areas responsibly. North Dakota’s geology records a landscape shaped by ancient seas, swamp forests, and massive ice sheets. Its badlands reveal the sediments of long-vanished ecosystems, while its glacial gravels carry stones transported from distant northern terrains. A Field Guide to the Identification and Collection of Rocks Across North Dakota is intended as a dependable companion in the field, encouraging responsible collecting and a deeper appreciation of the geologic history preserved across the northern plains.