Ancient sea, ice ages form landscape that attracts first St. Louisans: Revisiting St. Louis' history

Some time after the Beginning, much of what we call the Midwest was covered by a warm, shallow ocean. Millions of years of sediment and the remains of primordial creatures formed the limestone we rest upon.

Achingly slow collisions of continents pushed the land out of the water. Volcanic bulges created granite heights such as the St. Francois Mountains (near Farmington, Mo.). Dinosaurs roamed, just as the children’s books always say they did. The sea retreated south to the wide Delta flatland of the Bootheel.

The geological evidence suggests all of that took about 2 billion years, give or take a few million.

A series of ice ages beginning about 2.5 million years ago ground up the land roughly as far south as St. Louis, gouging valleys for massive runoffs of melt that created major rivers — including the Missouri, Mississippi and Illinois, which merge into the fertile bottomland of the great confluence. The last glacial retreat, 12,000 or so years ago, left behind the meandering river courses framed by the high limestone bluffs we know today.

The strategic convenience of the confluence attracted humans. The earliest evidence in this area is of arrowheads that were found at Mastodon State Park near Imperial, where nomadic clans probably killed mastodons for food 10,000 or 12,000 years ago. There’s not much more to go on.

The first clear indications of permanent settlement were the large earthen mounds that once dotted the land on both sides of the Mississippi. Only a few are left, the largest being Monks Mound near Collinsville. Clusters of mounds were constructed north of downtown and in East St. Louis, but later American settlers obliterated them.

The glory years of the Cahokia settlement, when it was a major city and trading center, ran for three or four centuries until about 1300 AD. Its people traded along the major waterways all the way to the Gulf of Mexico. Then they disappeared. No one knows why.

No tribe took their place with major settlements, but bands of Osage and Missouri regularly hunted along the Mississippi.

The first Europeans to pass by the future St. Louis were Jesuit Father Jacques Marquette and explorer Louis Jolliet, who drifted down the Mississippi River in 1673. French explorers soon claimed the river for their king. In 1699, his missionaries established the Holy Family church at present-day Cahokia, near a small village of Tamaroa Indians.

Other missionaries settled for a few years at the mouth of a small tributary known ever since as the River Des Peres — the River of the Fathers.

French colonists established other posts, including Ste. Genevieve and Fort de Chartres. In 1763, their king ceded the land east of the Mississippi to the British as spoils of the French and Indian War. (He also secretly deeded Louisiana to Spain, but nobody over here would learn that for nearly two years.)

In New Orleans, business partners Gilbert Maxent and Pierre Laclede obtained the colonial monopoly for fur trading in upper Louisiana colony. Laclede prepared for the long journey upriver to establish a trading post.

His destination was the great confluence.