Researchers in Mexico have discovered a large, lost Mayan city.  墨西哥的研究人员发现了一座失落的大型玛雅城市。  The major urban settlement, named Valeriana, is hidden deep in the southern forest of Campeche.  主要城市定居点瓦莱里亚纳 (Valeriana) 隐藏在坎佩切南部森林深处。  The discovery adds to existing knowledge about ancient Mayan settlements.  这一发现丰富了有关古代玛雅定居点的现有知识。  Valeriana was discovered by chance thanks to Lidar, or Light Detection and Ranging. It is a technology that uses lasers to map the Earth’s surface.  缬草是通过激光雷达（即光探测和测距）偶然发现的。这是一项使用激光绘制地球表面地图的技术。  The data used for the study came from around 122 square kilometers of high-quality Lidar data collected in 2013.  该研究使用的数据来自 2013 年收集的约 122 平方公里的高质量激光雷达数据。  The work, led by the Nature Conservancy in Mexico, was part of a forest monitoring project called Alianza. The project aimed to reduce emissions from tree cutting, or deforestation, and land damage.  这项工作由墨西哥大自然保护协会领导，是名为 Alianza 的森林监测项目的一部分。该项目旨在减少砍伐树木、森林砍伐和土地破坏造成的排放。  Researchers wrote in the study, published by Cambridge University Press, that "The discovery of Valeriana highlights the fact that there are still major gaps in our knowledge of the existence or absence of large sites within as-yet unmapped areas of the Maya Lowlands.”  研究人员在剑桥大学出版社发表的研究报告中写道，“缬草的发现凸显了一个事实，即我们对玛雅低地尚未绘制地图的地区是否存在大型遗址的了解仍然存在重大差距。”  Lidar technology revealed a major settlement, filled with buildings and agricultural infrastructure.  激光雷达技术揭示了一个主要定居点，充满了建筑物和农业基础设施。  The classical-era Maya civilization dates back to around 1800 to 1100 years ago. At the time, the Maya civilization grew its control over present-day southern Mexico and what are now Belize, El Salvador, Guatemala and Honduras.  古典时期的玛雅文明可以追溯到大约1800至1100年前。当时，玛雅文明扩大了对现今墨西哥南部以及现在的伯利兹、萨尔瓦多、危地马拉和洪都拉斯的控制。  In the study, the researchers identified a total of 6,764 structures, suggesting a populous ancient city.  在这项研究中，研究人员总共发现了 6,764 座建筑，表明这是一座人口稠密的古城。  The researchers will carry out further detailed study of the dataset – both remotely and in the field. The discovery serves as a way to better understand ancient Mayan urbanization and settlements.  研究人员将对数据集进行进一步详细的研究——远程和现场研究。这一发现为更好地了解古代玛雅城市化和定居点提供了一种方式。