Final answer:
The upward revision of land's value after purchase violates the historical cost principle in accounting, which dictates that assets should be recorded at the cost incurred at the time of the acquisition.
Step-by-step explanation:
The upward valuation of land subsequent to its purchase violates the historical cost principle. This accounting principle requires that an asset is recorded on the balance sheet at the price paid for it at the time of acquisition, rather than at its current market value. The idea is to maintain objectivity and reliability in the financial statements. Adjusting land values to market value after purchase introduces a subjective element and potential for manipulation, hence it is not in accordance with the historical cost principle which is fundamental to traditional accounting practices.