Fossil & Prairie Park Preserve Fossil Hunting Guide

Introduction

The Fossil & Prairie Park Preserve lies on the edge of Rockford, in Floyd County, north-central Iowa. It is a former clay pit worked for many years by the Rockford Brick & Tile Company, and when the digging stopped it left behind wide exposures of the Devonian Lime Creek Formation. That rock is packed with the shells and skeletons of animals that lived in a warm sea about 375 million years ago, and here, unlike most fossil sites, visitors are allowed to collect them. The fossils lie loose on the quarry floor and need no tools to gather.

The preserve is more than the quarry. It protects a remnant of native prairie and the historic beehive-shaped kilns of the old brick works, so a visit combines fossil collecting with prairie and industrial history. This guide covers how to reach the park, what you can collect, the geology of the Lime Creek Formation, the rules, and the practical details for a visit.

Location and Directions

The Fossil & Prairie Park Preserve is just outside Rockford, near 43.047 degrees north, 92.962 degrees west, in Floyd County. Rockford sits in north-central Iowa, and the preserve is a short distance from the town, reached by local roads and signed as a Floyd County park and Iowa state preserve.

There is a parking area at the preserve, along with the Fossil & Prairie Center, an interpretive building near the entrance. From the parking area, trails lead out to the open quarry floor where the fossils are collected and to the restored prairie and the historic kilns. The collecting area is the exposed rock and clay of the former pit.

The park is free and open year-round from sunrise to sunset, with no admission fee. The Fossil & Prairie Center keeps its own seasonal hours. Bring a container for your finds, since none are provided, and wear footwear suited to uneven ground. Check the weather before you go, because the clay of the quarry floor turns slick and sticky after rain.

What Fossils You'll Find

The Lime Creek Formation here is densely fossiliferous, and brachiopods are the most abundant find. These two-shelled marine animals weathered out of the shale lie scattered across the quarry floor, and several kinds occur, including large winged spiriferid brachiopods. Because the fossils are already loose on the surface, most collecting is simply a matter of walking slowly and picking them up.

Corals are common as well, both solitary horn corals and colonial forms, along with sections of crinoid stems, which appear as small round or star-shaped discs, and the lacy skeletons of bryozoans. Gastropod snails and other shells turn up in the mix. The fauna is a snapshot of a Late Devonian sea floor, and the preservation is good enough that the surface ornament on many shells is still clear. The site is well known among collectors for producing identifiable material with very little effort, which makes it a good place for families and first-time fossil hunters.

The best collecting follows weathering. Rain and frost break down the shale and free fresh fossils, so the surface is restocked over time, and a visit after wet weather, once the clay has drained enough to walk on, can be productive.

Geologic History

The Lime Creek Formation was deposited during the Late Devonian, roughly 375 to 372 million years ago. At that time Iowa lay in warm tropical waters near the equator and was covered by a shallow sea. Brachiopods, corals, crinoids, and other animals lived on and just above the sea floor, and their remains accumulated in the soft mud that later hardened into the shale and limestone of the formation. The result is a rock unit crowded with well-preserved marine fossils.

The reason the fossils are so easy to reach is industrial rather than natural. The Rockford Brick & Tile Company quarried the soft Devonian clay and shale to make brick and tile, and the digging exposed the fossil-bearing rock over a wide area. When the brickworks closed, the quarry was left open, and the site was set aside as a preserve. The old beehive kilns still stand near the collecting area as a reminder of the industry that, by accident, opened this window into the Devonian.

Collecting Rules and Regulations

Collecting is allowed at the Fossil & Prairie Park Preserve, and it is free. Visitors may collect fossils from the quarry area for a personal collection, and the park asks that people take only what they will keep for themselves rather than gathering in bulk. Tools are not needed, since the fossils lie loose on the ground, and casual surface collecting is the intended activity.

Keep to the collecting area of the former quarry and stay off the protected prairie remnant and away from the historic kiln structures. As a state preserve, the site protects its prairie and its industrial history alongside the fossils, so treat those areas as off limits for digging. If in doubt about where collecting is appropriate, ask at the Fossil & Prairie Center. Collecting is for personal, non-commercial use.

Safety

The main hazards are footing and weather. The quarry floor is uneven, and the clay soil becomes slippery and sticky after rain, so choose footwear to match the conditions and take care on the wet surface. Loose rock underfoot can shift, so watch your step, especially on any slopes at the edges of the pit.

The collecting area is open and exposed, so bring water and sun protection in summer and dress warmly in the cold months, since north-central Iowa has a wide range of weather. Watch for snakes in warm weather and keep children supervised on the uneven ground and away from the historic kiln structures. There are no cliffs or open water in the collecting area, so the chief concerns are slick clay, uneven footing, and exposure to the weather.

Sources

https://www.iowadnr.gov/places-go/state-preserves/fossil-prairie-park-state-preserve https://fossilcenter.wordpress.com/fossils/ https://www.mycountyparks.com/county/floyd/park/fossil-prairie-park-preserve-and-center