On July 25, 1806, in what is now Montana, Clark and his group reached a hill with soft sandstone cliffs. Clark named this sandstone bluff Pompeys Tower in honor of Sacagawea's son, Jean Baptiste, whom he had nicknamed Pomp or Pompey. He notes in his journal that
"This rock which I shall call Pompy's Tower is 200 feet high . . . The nativs have ingraved on the face of this rock the figures of animals [etc.] near which I marked my name and the day of the month & year."
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| Another view of Pompeys Pillar |
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Clark did indeed carve his name and the date on what is now known as Pompeys Pillar, and his signature can still be seen today — the only written mark still in existence that was made along the trail by a member of the expedition.
