Roman engineers erected marvelous aqueducts that are still in use today, but someone forgot to place the all-important keystone into this modern arch.

Arch Coal (NYSE:ACI) shares crumbled into a double-digit percent loss Friday after badly missing analyst estimates and slashing earnings expectations for the year ahead. Full-year 2009 earnings per share collapsed by 89% to $0.28 per share, even as revenue eroded by only 13%. Heavy reliance upon domestic coal markets continues to place Arch Coal in a difficult position relative to more global players like Peabody Energy (NYSE:BTU), but some early signs of stabilization at home and increasing opportunities abroad continue to leave this Fool looking beyond 2010 to a less troublesome long-term outlook.

Corroborating Peabody's observation of a rapid reduction in stockpiles starting in December, Arch estimates the peak U.S. coal stockpile at a monstrous (and all-time high) 207 million tons. In December, normalizing power demand and weather patterns, alongside rising natural gas prices, contributed to a rapid 12 million-ton reversal from the peak.

Also during December, Arch began to realize anticipated synergies at the world's largest coal mine. With the Jacob's Ranch operations -- acquired from Rio Tinto (NYSE:RTP) last year -- now fully integrated into Black Thunder, Arch expects annual synergies of $45 million to $55 million from here forward. When I compared valuations between the comparable Powder River Basin (PRB) assets of recent IPO Cloud Peak Energy (NYSE:CLD) and those from Jacob's Ranch, those synergies were not factored in. The Jacob's Ranch purchase will form a pillar of Arch Coal's long-term operating strength … but first the company has to navigate its way through some difficult times ahead.

Adapting to the permanent structural upheaval under way within the dynamics of the global coal market, wherein the Asia Pacific trade will increasingly dominate global demand, Arch Coal is positioning itself for greater emphasis upon servicing seaborne coal markets going forward. The company has scored a key leasehold at Otter Creek in the northern PRB region of Montana, which is situated more favorably to supply a seaborne trade. Arch Coal expects total U.S. coal exports to increase by at least 10 million tons during 2010.

In the meantime, I see too many solid opportunities within the sector to recommend Arch shares at this time. I stand firmly behind my selection of the five top coal picks, which itself is topped by the king of coal. Following a roughly 20% correction from its high on Jan. 11, even the Market Vectors Coal ETF (NYSE:KOL) looks ripe for the picking. Shares of Yanzhou Coal Mining (NYSE:YZC) have slipped enticingly from recent heights, and the phenomenal coking coal assets of Alpha Natural Resources (NYSE:ANR) position that miner beautifully for the ongoing transformation. I am waiting for the keystone to be placed back into the arch.

The "Coal" tag within the Motley Fool CAPS community lists 23 coal companies. Find out what other investors are saying about the stocks you're watching, or share your Foolish thoughts with us. CAPS is free and fun!

Fool contributor Christopher Barker wishes he could squeeze coal into diamonds. He can be found blogging actively and acting Foolishly within the CAPS community under the username TMFSinchiruna.He tweets. He owns shares of Arch Coal and Peabody Energy. The Motley Fool scrubs its disclosure policy before releasing it into the atmosphere.