Why You Can't See the Teeth in Calvert Cliffs — And Where They Actually Come From

The Calvert Cliffs are composed almost entirely of the Calvert Formation — a sequence of diatomaceous clay and silty marl deposited in a shallow, warm, nutrient-rich sea during the Miocene, approximately 10–18 million years ago. The formation is rich in microscopic plankton remains (the diatomite component), which gives the exposed clay a distinctive light grey to white color and a crumbly, almost chalky texture.

Within this clay matrix, fossil material is scattered throughout — shellfish, whale bones, ray fragments, and yes, shark teeth. But they are not distributed evenly or obviously. They occur as isolated specimens within a massive, homogeneous matrix. The cliff face is essentially a solid block of fine-grained marine sediment with fossils randomly embedded at unpredictable intervals and depths. A tooth could be sitting 10 feet into the cliff face, completely invisible from the outside. Another might be 2 inches behind the surface and still completely hidden — the surrounding clay is the same color as the tooth matrix, and there is no visual contrast at distance.

The critical additional factor is friability. The Calvert Formation clays are soft, water-saturated, and actively eroding. What you observe on the cliff face on any given day is not a static mineralized exposure. It is wet, unstable material that has been raining down onto the beach continuously since the cliffs formed.

Teeth do not emerge gradually from the cliff face like specimens in a museum display case. The actual mechanism is far more dramatic and far less photogenic. Sections of the overhanging cliff — sometimes several tons of clay at once — calve off in blocks during rain events, freeze-thaw cycles, and wave undercutting. These blocks fall to the beach and immediately begin breaking down.

As the clay block disintegrates (accelerated by rain, wave action, and physical contact as visitors walk over the material), the co-embedded fossils become free. A tooth that was locked inside 10 feet of clay yesterday may be sitting on the surface of a disintegrated block tomorrow. The Chesapeake Bay's erosive wave action further refines the process — as the disintegrated clay washes back into the bay, the denser fossil material (tooth enamel and bone are significantly denser than the surrounding diatomite clay) is left behind on the beach as a lag deposit.

This is why the productive zone at Calvert Cliffs is always at the cliff base, not mid-face or at height. The base is where fresh fall material accumulates, where wave action is actively washing out the clay matrix, and where the lag deposit of dense fossils concentrates at the water's edge. The teeth are not "in the cliff face" in any visually obvious sense — they are in the sediment that used to be the cliff face, currently in the process of being delivered to the beach.

The most productive hunting at Calvert Cliffs is at the waterline at low tide, specifically at the junction between the sandy beach and the wave-washed cliff base. This zone is where the lag deposit concentrates: clay has been washed away, leaving behind shell hash, shark teeth, and bone fragments on a relatively firm substrate.

After a storm or significant rain event, new cliff fall material will be present — large grey clay blocks of various sizes around the cliff base. These are worth investigating closely. Get down low and search the surface of recently disintegrated blocks. Fresh fall clay hasn't had time to fully deflate; the teeth may be projecting only a few millimeters from the surface or may require brushing the clay aside with a finger.

The beach at Calvert Cliffs State Park runs approximately 1.7 miles between the park boundary and the cliff terminus. The productive zone is asymmetric: the southern section of the beach near the cliff base tends to produce more megalodon and large shark material because the Calvert Formation there intercepts older, deeper strata (lower member of the Calvert Formation, approximately 15–18 Ma) that contain material from the peak megalodon period. The northern section produces somewhat younger Choptank Formation material with different fauna.

The cliffs expose three distinct Miocene formations stacked in ascending order (older at the bottom, younger toward the top), each representing a somewhat different depositional environment and fauna.

The Calvert Formation (basal section, up to 15–18 million years old) is the oldest exposed unit. This is the deep Miocene — warm Paratethyan-influenced water, abundant elasmobranchs, and the window when *Otodus megalodon* was growing to maximum size. Calvert Formation teeth are the most prized: the largest megalodon teeth, tiger shark teeth, early *Carcharodon* lineage specimens, and abundant *Hemipristis* (snaggletooth shark) material.

The Choptank Formation (above the Calvert, approximately 12–15 million years old) represents a somewhat shallower and cooler water environment. The fauna shifts toward species more tolerant of temperature variation. Teeth here tend to be smaller on average, with a higher proportion of small lamnid and carcharhinid species. Large whale bone and cetacean rib material is common in the Choptank.

The St. Marys Formation (topmost exposed unit, approximately 8–12 million years old) represents the youngest Miocene sequence. The sea was cooling toward the Late Miocene climatic deterioration. Megalodon teeth from the St. Marys tend to be smaller, reflecting the declining size of the species as ocean temperatures dropped toward Pliocene levels.

A distinct and underappreciated source of Calvert Cliff material is the Chesapeake Bay floor itself. The bay occupies a tectonic valley formed partly by the Chesapeake Bay Impact Structure — a 35-million-year-old impact crater buried beneath the bay's southern end. The bay floor sediments include reworked Miocene material from the same Calvert and Choptank Formations that form the cliffs onshore.

During storm events and significant current action, bay bottom sediments agitate and transport reworked fossil material northward and onto beaches. Teeth found on Calvert Cliffs beaches after major storms sometimes include material with a different preservation signature than fresh cliff fall — more abraded, slightly rolled, with a different color spectrum. These are bay-floor reworked specimens, sometimes representing teeth that eroded into the bay centuries ago and have been in the bay-floor lag deposit since.

This dual-source system means that productive hunting after storms represents two different input streams: fresh cliff fall from recent erosion events, and bay-floor reworked material from storms agitating ancient lag deposits on the bay bottom. The hunter is benefiting simultaneously from geology happening right now (cliff erosion) and from material that was deposited on the bay floor potentially thousands of years ago.