Had they waited a minute longer they would have been swept into the Missouri just above the Great Falls. They reached the top in safety, and there found York, who had left them just before the storm to hunt some buffalo. They pushed on to camp where the rest of the party had already taken shelter, and had abandoned all work for that day. While the men were building a new boat of skins, Captain Lewis spent much time studying the animals, trees, and plants of the region, making records of them to take home. Ever since their arrival at the falls they had heard a strange noise coming from the mountains a little to the north of west. "It is heard at different periods of the day and night," Lewis wrote, "sometimes when the air is perfectly still and without a cloud, and consists of one stroke only, or of five or six discharges in quick succession. It is loud, and resembles precisely the sound of a six-pound piece of ordnance at the distance of three miles. The Minnetarees frequently mentioned this noise like thunder, which they said the mountains made; but we paid no attention to it, believing it to have been some superstition, or perhaps a falsehood. The watermen also of the party say that the Pawnees and Ricaras give the same account of a noise heard in the Black Mountains to the westward of them. The solution of the mystery given by the philosophy of the watermen is, that it is occasioned by the bursting of the rich mines of silver confined within the bosom of the mountain." Early in July the new boat was finished. It was very strong, and yet could be carried easily by five men. But when it was first launched they found that the tar-like material with which they had covered the skins that made the body of the boat would not withstand water, and so the craft leaked. After trying to repair the boat for several days they finally decided to abandon it. Putting all their luggage into the canoes they resumed their journey up the river. As the canoes were heavily loaded the men who were not needed to paddle them walked along the shore. The country here was very picturesque. At times they climbed hills that gave them wide views of open country never explored by white men; again they waded through fields of wild rye, reminding them of the farm lands of the East; sometimes their path wound through forests of redwood trees, and always they could see the high mountains, still snow-capped. The glistening light on the mountain tops told the explorers why they were called the Shining Mountains.