Their trade, as Dr. Rau has shown, was widespread, extending probably from Lake Superior to the Gulf, and possibly to Mexico.[83] They constructed canals by which lake systems were united, a fact which Mr. Conant has recently shown to be well established in Missouri.[84] Their defences were numerous and constructed with reference to strategic principles, while their system of signals placed on lofty summits, visible from their settlements and communicating with the great watercourses at immense distances, rival the signal systems in use at the beginning of the present century. Their religion seems to have been attended with the same ceremonies in all parts of their domain. That its rites were celebrated with great demonstrations is certain. The sun and moon probably were the all-important deities, to whom sacrifices (possibly human) were offered. We have already alluded to the development in architecture and art which marked the possible transition of this people from north to south. Here we see but the rude beginnings of a civilization which no doubt subsequently unfolded in its fuller glory in the valley of Anahuac, and spreading southward engrafted a new life upon the wreck of Xibalba. Though there is no evidence that the Mound-builders were indigenous, we must admit that their civilization was purely such—the natural product of climate and the conditions surrounding them.[85] [Illustration: Copper Relics from Wisconsin. (From photos furnished by Prof. Butler.)] CHAPTER II. ANTIQUITY OF MAN ON THE WESTERN CONTINENT. Antiquity of the Mounds — No Tradition of the Mound-builders — Vegetation Covering the Mounds — Age of Mound Crania — Probable Date of the Abandonment of the Mounds — Ancient Shell-heaps — Man’s Influence on Nature — Supposed Testimony of Geology — Agassiz on the Floridian Jaw-bone — Remains on Santos River — The Natchez Bone — Remains on Petit Anse Island — Brazilian Bone caves — Dr. Koch’s Pretended Discoveries — Ancient Hearths — Age of the Mississippi Delta — Dr. Dowler’s Discovery at New Orleans — Dr. Abbott’s Discoveries in New Jersey — Discoveries in California — Inter-Glacial Relics in Ohio — Crania from Mounds in the North-west — No Evidences as yet Discovered Proving Man’s Great Antiquity in America.